Engine lite- Dealer keeps blowing me off

Have an 06 Silverado. The engine light keeps coming on. I have had the codes cleared four times. One at my tire/repair shop 3 at the dealership. All codes (sorry I don’t have the exact code number) refer to fuel being lean or rich. Dealership keeps saying I buy cheap gas. I buy gas for the truck at the same place I buy for my other cars and one of those is a Mustang Gt which sits in the garage all winter and I have never had an issue. Dealership also told me I don’t drive my car enough and the ethanol in the fuel is dissipating? Anyhow, I keep arguing with them that something other than that keeps causing this problem but they refuse to look further. Any advice or suggestions as to what parts may need to be cleaned or replaced? (aside from finding a new dealership) Truck has 111K miles.

First…stay away from this dealer because they know zip about mechanical issues. Next…have your codes read for free at a large auto parts store and post them here exactly as they are given to you. Someone here will tell you what is wrong. Then find a good independent mechanic to actually repair your truck. Stop wasting your money at dealerships on vehicle repairs in the future.

Most of the time with a lean code on these trucks I have found the problem to be with the intake gaskets. Missileman’s correct, the dealer will do you no good. Find an independent shop, not a chain shop to help you.

Something here doesn’t sound right. For the $100+ that the dealer charges for an engine performance/check engine light diagnosis, you should have been given a long list of testing and fault codes and some required and recommended repairs.

Most people complain about getting too large an estimate from the dealer for a bunch of work, some of which may not be needed. You seem to have the opposite problem.

What exactly has the dealer done so far to try to correct the problem?

The dealership has done nothing to fix the continued error code. I have taken the truck there 3 times to have the code read, cleared and hopefully fixed. What they are good at is telling me a bunch of bs, blaming me for either not driving the truck enough and allowing the ethanol to break down, or buying cheap gas. I have no other issues with the other 3 cars I own and I buy gas for them at the same place. Thanks for the tips. I am going to get to codes read “again” and cleared again. I will post what I find. I am now doing my own research into this problem. Seems to be a common problem not limited to Chevy’s. So I am sure I will find the culprit. Will post more later.

Originally only went to the dealership because I was told there was an update to the computer that needed to be down loaded. Dealership had no idea what I was talking about and said there was no available updates to download

Okay. P0172 fuel trim bank one. It gave me a few options as to what could be the problem. Will start with number one MAF sensor. Will replace that today and clear codes and see what happens. Other options given : O2 sensor, ignition misfire - repair or fuel injector problem. Truck is showing no signs of loss of power or any signs of problem/hesitation or what not, so I am thinking it is not a fuel injector problem. MAF is in line with other research I have done.

What say you?

Do you have a K&N filter in it? If so clean the Maf with sensor safe cleaner and put in a new air filter. I would clean Maf and replace filter if dirty. Could be intake leak. Sqiurt around intake with starter fluid. If idle increases, then it’s leaking.

Just clean the MAF, do not replace it. They are very expensive and will usually give you a PO100 code if they actually go bad. Use a spray MAF cleaner, takes little time.

Your code is for running rich. Typically a dirty MAF will run lean. This is also true for any leaks in the intake ducts. You may have a leaky or dirty injector so I would run a can or two of Techron through your gas tank. It will often clean up the injectors enough.

If none of this works, then you may need a new MAF sensor as a burned out MAF sensor does make the engine run very rich. Usually you will have trouble with the engine dying every time you come to a stop. This will be intermittent at first and get worse with time.

Well, one idea is to see if the problem goes away if you buy gas at a place the dealer recommends, and drive the truck 50 miles every day. If that fixes the problem, at least you know they are on the right track. I doubt they are purposely leading you astray. In their experience when these trucks aren’t driven frequently or use a certain fuel supplier this problem usually develops.

FYI, “fuel trim” is a engine-computer measured parameter which shows the difference between how much gasoline the engine is requiring based on the O2 sensor compared to what the computer thinks it should require based on the rpm/load/coolant temp/intake manifold pressure/maf sensor readings. If everything in the engine was copasetic and working correctly, the fuel trim would be close to zero; i.e. the O2 sensor would match up with the other parameters. So a significant difference mean something isn’t working correctly. I expect you know already it could be any of the above. There are tests to determine what it is. But those tests might prove expensive to do. So the dealership seems to be saying “In our experience you won’t like the bill we’ll present you for all these tests and parts replacement and you’ll still have the problem anyway until you drive the truck more frequently and use the gas brand we tell you to.”

Which is why I’m suggesting you try what they say first. You can find more at the following link, found by Googling “Silverado and the code you posted”. Best of luck.

I have done what the dealership has recommended. Does not seem to matter where I buy gas and I drive the truck during winter months and still have the codes showing. I don’t buy the not driving the car enough or gas problem as I have a Mustang GT that I park all winter long (fuel at the same spots) and can pull it out of the garage in the spring and have no issues what so ever. The code says fuel trim lean/rich. It does not specify which. Dealership also never ever showed me or told me what parts could be causing the problem (as the auto parts store that scanned the latest code, gave me a print out of possible causes) The dealership just kept blaming me for bad gas or not driving the truck enough. My research has found that his is a rather common code and with proper diagnostics the part or parts that are causing the code can be found and repaired.

I have replaced the MAF sensor cause it was an easy fix and with core exchange rather in expensive. I have cleared the codes, but the engine light has returned. Will be taking it to a service shop this week.

I do thank each of you for your input. When I finally figure out what it was, I will let you know.

Using your Mustang as the benchmark is absolutely useless as that vehicle is not being used even remotely the same as the Silverado, so you really should throw that theory out the window. As I believe Keith stated…DO NOT Simply replace the MAF…they are NOT cheap and often simply need a cleaning with either Brake Clean Spray…or MAF Spray cleaner…which is basically the same.

Fuel can and does vary WIDELY from place to place… SO… I would try a new station…AFTER running a concentrated Fuel Injector Cleaner thru the system. Buy a bottle of the upper grade of Techron…and run it thru with about HALF the recommended amount of fuel so as to concentrate the solution even further. After the tank of Techron is run thru…fill up at a DIFFERENT STATION and see what you get. If there is a piece of debris in one of the injectors it will drip raw and NOT atomized fuel into whichever cylinder it is complaining of. If and when I find the rare instance of a stuck OPEN injector…I can USUALLY solve the issue by grounding out the negative side of the injector so as to fully open the injector and hope to pass the debris…it does work…not very common of an occurrence but I’ve fixed several in the past in this manner. See what you get after the MAF Clean…a throttle body clean wouldn’t hurt you either while you’re at it…Run the Techron thru the system and fill up at a different station…See what you get…you may get lucky with those simple steps. If not let us know the situation so we can advise further.


Have you tried replacing the intake gasket. An intake leak will cause this. If the dealer is blowing you off, find a independent mechanic listed in the Mechanic Files link above.

P0172 Is a code for System too rich bank 1 as Keith alluded to… Intake gasket leaks can only create a Lean condition…NEVER a rich condition.


@Honda Blackbird I misread it and thought they were having a lean condition. How about a vacuum leak?