2007 Chevy Silverado 1500 Classic - P0172 & P0175 Rich Codes Finally Diagnosed and Fixed
video description
Date: 2025-12-23
Related videos
Comments and reviews: 20
RussellBooth1977
I got my 2002 model Holden VY SS Commodore inspected for registration last Friday morning (December 12) & afterwards while I was only driving at 50 km/h (about 30 mph) a check engine symbol turned on.
I drove for another 5 kilometres (3 miles) & the check engine symbol turned off by itself, when I got home I plugged in my Vident scan tool & retrieved a P0327 code for the front knock sensor which I cleared & the fault never returned.
I replaced both knock sensors with Wells Knock sensors which are good quality U. S. made knock sensors as well as an aftermarket knock sensor wiring harness 6 years ago after one sensor which was a Chinesium knock sensor & the other one was another good quality sensor which just corroded & failed 10 years after I replaced it in 2009.
I never got any knock sensor codes until last Friday & that code has never come back, it's a Gen 3 Chevrolet LS1 V8 engine & I also never pressure clean or hose off the engine because water can short out & corrode the knock sensors which I learned the hard way in 2009.
I washed the car on Thursday the 11th so I was wondering if there's any possibility that water intrusion into the PCM connector pins caused it, Ivan from PHAD had that issue with a 4. 8 litre GMC truck a few years ago where water shorted out the PCM connector pins for the knock sensors which was causing codes to be set even with new knock sensors fitted.
I measured the resistance of each knock sensor measured at 99. 7 & 99. 8 K Ohms from each knock sensor terminal on the 2 pin connector to the ground point which was the cylinder head.
I measured the voltage from each of the 2 pins on the PCM to the sane ground point & it was 17. 8 millivolts which is good so I have left it alone, I was wondering if it was also because the fuel tank level was low & it was picking up bad fuel, like it could've had bad fuel which caused a severe knock but I didn't notice the engine running rough or anything.
I am just going to leave it alone!
reply
I got my 2002 model Holden VY SS Commodore inspected for registration last Friday morning (December 12) & afterwards while I was only driving at 50 km/h (about 30 mph) a check engine symbol turned on.
I drove for another 5 kilometres (3 miles) & the check engine symbol turned off by itself, when I got home I plugged in my Vident scan tool & retrieved a P0327 code for the front knock sensor which I cleared & the fault never returned.
I replaced both knock sensors with Wells Knock sensors which are good quality U. S. made knock sensors as well as an aftermarket knock sensor wiring harness 6 years ago after one sensor which was a Chinesium knock sensor & the other one was another good quality sensor which just corroded & failed 10 years after I replaced it in 2009.
I never got any knock sensor codes until last Friday & that code has never come back, it's a Gen 3 Chevrolet LS1 V8 engine & I also never pressure clean or hose off the engine because water can short out & corrode the knock sensors which I learned the hard way in 2009.
I washed the car on Thursday the 11th so I was wondering if there's any possibility that water intrusion into the PCM connector pins caused it, Ivan from PHAD had that issue with a 4. 8 litre GMC truck a few years ago where water shorted out the PCM connector pins for the knock sensors which was causing codes to be set even with new knock sensors fitted.
I measured the resistance of each knock sensor measured at 99. 7 & 99. 8 K Ohms from each knock sensor terminal on the 2 pin connector to the ground point which was the cylinder head.
I measured the voltage from each of the 2 pins on the PCM to the sane ground point & it was 17. 8 millivolts which is good so I have left it alone, I was wondering if it was also because the fuel tank level was low & it was picking up bad fuel, like it could've had bad fuel which caused a severe knock but I didn't notice the engine running rough or anything.
I am just going to leave it alone!
reply
tommyhawks856
Here is a tip for anyone replacing the knock sensors on the LS engine. Each sensor sets in its own little well in the valley plate under the intake manifold. When you replace the sensor(s) it would be prudent to use some RTV to build up a wall of RTV around the wells for the knock sensors. Leave about 1/2 of open space in the RTV around the back side of the wells. Eric mentioned the foam that is along the front of the intake manifold that goes all the way down to the valley plate the sensors reside in. The foam is about as porous as a sponge, and water will usually get past the foam when people wash their engines. This water settles into the sensor wells and pitting and corrosion of the sensors start to take place. The RTV built up along the front and sides of the well help to divert the water away from the wells, and you do not apply the RTV all the way around the wells. Leave the 1/2 gap on the backside of the wells to allow water to drain out of the wells should any water make its way into the wells. Another tip is if you are replacing 1 sensor, replace both of them at the same time, along with the short harness for the sensors. It's an easy and fairly inexpensive job to do. That is my DIY tip for the day.
reply
Here is a tip for anyone replacing the knock sensors on the LS engine. Each sensor sets in its own little well in the valley plate under the intake manifold. When you replace the sensor(s) it would be prudent to use some RTV to build up a wall of RTV around the wells for the knock sensors. Leave about 1/2 of open space in the RTV around the back side of the wells. Eric mentioned the foam that is along the front of the intake manifold that goes all the way down to the valley plate the sensors reside in. The foam is about as porous as a sponge, and water will usually get past the foam when people wash their engines. This water settles into the sensor wells and pitting and corrosion of the sensors start to take place. The RTV built up along the front and sides of the well help to divert the water away from the wells, and you do not apply the RTV all the way around the wells. Leave the 1/2 gap on the backside of the wells to allow water to drain out of the wells should any water make its way into the wells. Another tip is if you are replacing 1 sensor, replace both of them at the same time, along with the short harness for the sensors. It's an easy and fairly inexpensive job to do. That is my DIY tip for the day.
reply
TimfromAlabama
Just do what I did and hollow out the cats and let her run. Mine runs rich, but that's because she's catless and I change the oil every 3500 miles so I don't really worry about all of that anymore. Check engine light. that's a new dash illuminator. lol. 2005 Silverado and she runs good even though rich, and drives good. I don't drive it much now with the newer 2019 we bought, so she probably hasn't got over 100 miles on it since September, if that much. I only drive it back and forth to pay the bills. And we don't have inspections here so not an issue to worry about. I will replace the cats when I get the dough and then worry about the rest after that, but at how much they cost both parts and labor I imagine this thing will run until it don't anymore, or I'm gone from this earth. Just gotta keep that other truck up since the wife drives it. Mama is happy so I guess it's OK. LOL. Cheers.
reply
Just do what I did and hollow out the cats and let her run. Mine runs rich, but that's because she's catless and I change the oil every 3500 miles so I don't really worry about all of that anymore. Check engine light. that's a new dash illuminator. lol. 2005 Silverado and she runs good even though rich, and drives good. I don't drive it much now with the newer 2019 we bought, so she probably hasn't got over 100 miles on it since September, if that much. I only drive it back and forth to pay the bills. And we don't have inspections here so not an issue to worry about. I will replace the cats when I get the dough and then worry about the rest after that, but at how much they cost both parts and labor I imagine this thing will run until it don't anymore, or I'm gone from this earth. Just gotta keep that other truck up since the wife drives it. Mama is happy so I guess it's OK. LOL. Cheers.
reply
jeffco908
MAF sensor may have fixed why it increased alcohol content but other shop failed by not resetting content value. I have fixed a ton of these with MAF actual VS desired being off by more than 1 g/s. ECM continuously incrementing the alc% trying to compensate for the difference. Once i saw the pattern i swapped maf sensors back and forth and confirmed within about a month alc content would rise with the 2 readings off set. Content would remain at base level when they were near 0 difference. Even had a guy come by my house after he replaced his maf sensor and truck still ran rich and set p0172 and p0175. I reset the content value and it was fixed. looked at MAF reading and were near identical desired vs actual. He had old sensor so we swapped it in and actual and desired were 1. 2 g/s different.
reply
MAF sensor may have fixed why it increased alcohol content but other shop failed by not resetting content value. I have fixed a ton of these with MAF actual VS desired being off by more than 1 g/s. ECM continuously incrementing the alc% trying to compensate for the difference. Once i saw the pattern i swapped maf sensors back and forth and confirmed within about a month alc content would rise with the 2 readings off set. Content would remain at base level when they were near 0 difference. Even had a guy come by my house after he replaced his maf sensor and truck still ran rich and set p0172 and p0175. I reset the content value and it was fixed. looked at MAF reading and were near identical desired vs actual. He had old sensor so we swapped it in and actual and desired were 1. 2 g/s different.
reply
thomasevans6045
I used to drive 2006 Chevy Silverado 1500 5. 3 4x4, 2 in fleet and I actually was assigned both at different times. First one 326, 000 miles when I turned it in for a 2012. 2012 was a bad buy by company owner, Houston flood truck. Got 2nd 2006. It did have a new engine due to someone using cruise control from Nashville to Knoxville. Pulling a 2 ton trailer and bent a lifter. The owner had the maintenance guy put a gps tracker on it and wired it wrong, shorting out main fuse panel. It had 350, 000 miles when I gave it up for a 2014 Tundra 4x4( that had electronic issues. Gave that one up when I walked into a better work situation.
reply
I used to drive 2006 Chevy Silverado 1500 5. 3 4x4, 2 in fleet and I actually was assigned both at different times. First one 326, 000 miles when I turned it in for a 2012. 2012 was a bad buy by company owner, Houston flood truck. Got 2nd 2006. It did have a new engine due to someone using cruise control from Nashville to Knoxville. Pulling a 2 ton trailer and bent a lifter. The owner had the maintenance guy put a gps tracker on it and wired it wrong, shorting out main fuse panel. It had 350, 000 miles when I gave it up for a 2014 Tundra 4x4( that had electronic issues. Gave that one up when I walked into a better work situation.
reply
1wheeldrive751
I don’t think Eric likes to get too political, but problems like this were absolutely caused by the big push to increase ethanol fuel a couple of decades ago. There was never a good reason to switch to ethanol. It was folly from day 1.
Politics is a funny, funny thing. One minute they want to reduce our oil dependency on foreign oil even though we had massive oil production capability. And then a few years later on they want us to reduce CO2 emissions into the atmosphere, which is a necessity for our continued survival on the planet.
The ridiculous requirements that result from your bad votes are things like this.
reply
I don’t think Eric likes to get too political, but problems like this were absolutely caused by the big push to increase ethanol fuel a couple of decades ago. There was never a good reason to switch to ethanol. It was folly from day 1.
Politics is a funny, funny thing. One minute they want to reduce our oil dependency on foreign oil even though we had massive oil production capability. And then a few years later on they want us to reduce CO2 emissions into the atmosphere, which is a necessity for our continued survival on the planet.
The ridiculous requirements that result from your bad votes are things like this.
reply
DrFiero
Pretty sure the '07 shown here was a return type fuel system - but my '08 is a dead headed (returnless) system. It always ran rich right after I got it. finally got around to testing the actual (not scan tool indicated) fuel pressure. It was about 90psi at idle! Seems water had got into the FSCM (brilliant job putting it over top of the spare tire at the back GM) and was driving the fuel pump at 100% duty cycle. Dismantled it, cleaned it out, fix a trace or two. Sealed the snot out of the case. Been fine for coming on 10 years now.
reply
Pretty sure the '07 shown here was a return type fuel system - but my '08 is a dead headed (returnless) system. It always ran rich right after I got it. finally got around to testing the actual (not scan tool indicated) fuel pressure. It was about 90psi at idle! Seems water had got into the FSCM (brilliant job putting it over top of the spare tire at the back GM) and was driving the fuel pump at 100% duty cycle. Dismantled it, cleaned it out, fix a trace or two. Sealed the snot out of the case. Been fine for coming on 10 years now.
reply
tdubbz90
Just because you don't have e85 near you doesn't mean anything. ethanol in regular fuel is getting out of hand. If it was e85 it would be higher than 30 percent. These trucks hate alcohol in the fuel even on the L59 flex fuel trucks. I've dealt with it a lot. Had the same issue on two of my GMT800 suburbans I owned. First time took forever to fix and I didn't have a fancy scan tool that would reset the fuel composition so that was fun.
reply
Just because you don't have e85 near you doesn't mean anything. ethanol in regular fuel is getting out of hand. If it was e85 it would be higher than 30 percent. These trucks hate alcohol in the fuel even on the L59 flex fuel trucks. I've dealt with it a lot. Had the same issue on two of my GMT800 suburbans I owned. First time took forever to fix and I didn't have a fancy scan tool that would reset the fuel composition so that was fun.
reply
Bowhunters6go8xz6x
I've been very fortunate with my 2001 GMC Sierra 5. 3L just over 150, 000 miles which is low mileage for the years, still has almost all its original parts. I've used nothing but QT/QuikTrip gasoline since it was new, it is a Tier 1 gasoline with a lot of detergents to help keep the engine clean. Engine runs great and idles so smooth you cannot hear it. Merry Christmas and Happy New Year to all here!
reply
I've been very fortunate with my 2001 GMC Sierra 5. 3L just over 150, 000 miles which is low mileage for the years, still has almost all its original parts. I've used nothing but QT/QuikTrip gasoline since it was new, it is a Tier 1 gasoline with a lot of detergents to help keep the engine clean. Engine runs great and idles so smooth you cannot hear it. Merry Christmas and Happy New Year to all here!
reply
billybobbarker3175
My 2000 GMC Sierra LM7 5. 3 runs super duper smooth. Just finished a long 8hr drive today through the snow and -5F weather. Had the scanner on it for awhile. Short trims were bouncing at -3 to 5 on both banks. But the long term trims were at 20 to 23 on both sides. What does that mean
Reaching for straws as for where to start looking. Or do I look at all There are no codes and it runs well as is.
reply
My 2000 GMC Sierra LM7 5. 3 runs super duper smooth. Just finished a long 8hr drive today through the snow and -5F weather. Had the scanner on it for awhile. Short trims were bouncing at -3 to 5 on both banks. But the long term trims were at 20 to 23 on both sides. What does that mean
Reaching for straws as for where to start looking. Or do I look at all There are no codes and it runs well as is.
reply
LMacNeill
I can't think of a single sensor that I would buy aftermarket and be happy with. Same with fuel injectors and spark plugs and coils. You ALWAYS get OEM for those parts, unless they've been discontinued by the OEM. Well, ok, aftermarket spark plugs are probably fine, I suppose -- you don't have to go to the dealer to get 'em, but they'd better be made by the company that made 'em for the OEM.
reply
I can't think of a single sensor that I would buy aftermarket and be happy with. Same with fuel injectors and spark plugs and coils. You ALWAYS get OEM for those parts, unless they've been discontinued by the OEM. Well, ok, aftermarket spark plugs are probably fine, I suppose -- you don't have to go to the dealer to get 'em, but they'd better be made by the company that made 'em for the OEM.
reply
autorepair
A fuel alcohol composition reset doesn't fix anything, it just kicks the problem a few months down the road. Was hoping to get an answer how & why the virtual alcohol detection obsesses over having 30% alcohol when it never does. Nobody can give a straight answer.
The correct procedure is to have a tuner shut off flex fuel. Only way to not have this keep coming back.
reply
A fuel alcohol composition reset doesn't fix anything, it just kicks the problem a few months down the road. Was hoping to get an answer how & why the virtual alcohol detection obsesses over having 30% alcohol when it never does. Nobody can give a straight answer.
The correct procedure is to have a tuner shut off flex fuel. Only way to not have this keep coming back.
reply
rhkips
I have a friend that lives less than a mile from where he works, and his poor truck thinks it's running on 90% ethanol every few months. He's been interested in automotive, so I just bought him a little Autel for Christmas and walked him through how to look at and reset his alcohol content. Fortunately he asked me to look at his truck before he dragged it to a shop!
reply
I have a friend that lives less than a mile from where he works, and his poor truck thinks it's running on 90% ethanol every few months. He's been interested in automotive, so I just bought him a little Autel for Christmas and walked him through how to look at and reset his alcohol content. Fortunately he asked me to look at his truck before he dragged it to a shop!
reply
MrLKHen
I live in Houston and after watching your diagnostic skills, debate whether I should make the drive to NY for you to fix issues. I’m sorry, I just don’t have that much confidence in local mechanics. Most just want to R&R until issue is resolved. How do you find a Mx that has your skill set without spending a lot of money in trial and error in finding a good Mx
reply
I live in Houston and after watching your diagnostic skills, debate whether I should make the drive to NY for you to fix issues. I’m sorry, I just don’t have that much confidence in local mechanics. Most just want to R&R until issue is resolved. How do you find a Mx that has your skill set without spending a lot of money in trial and error in finding a good Mx
reply
snowdragon930
Just did one a couple days ago with the content showing 80%. Still waiting to hear if the fuel trims came down again. I have one question. when you said populate the cells. I didnt know what you meant by that. If you could please elaborate like Mr Whoopee did with his 3d BB (Blackboard) to Tennessee Tuxedo and the Walrus. Thank you much Eric O.
reply
Just did one a couple days ago with the content showing 80%. Still waiting to hear if the fuel trims came down again. I have one question. when you said populate the cells. I didnt know what you meant by that. If you could please elaborate like Mr Whoopee did with his 3d BB (Blackboard) to Tennessee Tuxedo and the Walrus. Thank you much Eric O.
reply
nonyabiz2777
Mr O is a product of a old school tough as he double tooth pick father. A work ethic from working at an early age with a mentor that loved his craft and taught his son the value of honest fair work. Bravo Mr and Mrs O we are porous to know your children will be just as good but most likely better than mom and dad. Nice work as always.
reply
Mr O is a product of a old school tough as he double tooth pick father. A work ethic from working at an early age with a mentor that loved his craft and taught his son the value of honest fair work. Bravo Mr and Mrs O we are porous to know your children will be just as good but most likely better than mom and dad. Nice work as always.
reply
autorepair
There is a rumor going around the greater Avoca Metropolitan Area that Eric O has increased property values by about fifteen percent. Apparently, a lot of people want to live close to a celebrity You Tube mechanic. Not for the celebrity part, for the mechanic part. Merry Christmas and Happy New Year to the SMA family!
reply
There is a rumor going around the greater Avoca Metropolitan Area that Eric O has increased property values by about fifteen percent. Apparently, a lot of people want to live close to a celebrity You Tube mechanic. Not for the celebrity part, for the mechanic part. Merry Christmas and Happy New Year to the SMA family!
reply
WreckDiver99
Eric, Eric, Eric. my 1999 Tahoe is still cranking out the hps! Love that truck. Sits outside (NOT happy about that, but she still keeps trucking. Just replaced my Rotor as it was missing, and when we pulled that rotor we were pretty shocked at how worn it was. then again. it has been a few hundred thousand miles. LOL!
reply
Eric, Eric, Eric. my 1999 Tahoe is still cranking out the hps! Love that truck. Sits outside (NOT happy about that, but she still keeps trucking. Just replaced my Rotor as it was missing, and when we pulled that rotor we were pretty shocked at how worn it was. then again. it has been a few hundred thousand miles. LOL!
reply
danieljurgill1681
But what was the root cause for a 30 % ethanol reading in the PCM Will the customer be back in 3 weeks Was the vehicle a family car that is always on the Empty Does this add water condensation indirectly always running near empty Was E85 gasoline put in by mistake How does the PCM determine the ethanol content
reply
But what was the root cause for a 30 % ethanol reading in the PCM Will the customer be back in 3 weeks Was the vehicle a family car that is always on the Empty Does this add water condensation indirectly always running near empty Was E85 gasoline put in by mistake How does the PCM determine the ethanol content
reply
justsumguy2u
Watching this vid makes me glad I moved to Florida many years ago---76 degrees today. But I digress. So many mechanics (if you want to call them that) are living in the 70's---being a parts replacer in 2025 doesn't work. It's imperative to have a decent scan tool, know how to use it, and know what to look for
reply
Watching this vid makes me glad I moved to Florida many years ago---76 degrees today. But I digress. So many mechanics (if you want to call them that) are living in the 70's---being a parts replacer in 2025 doesn't work. It's imperative to have a decent scan tool, know how to use it, and know what to look for
reply
Add a review, comment
Other channel videos
