Melvin

Hello guys,
Need help, having this check engine light on for the past month now. Was scanned at a dealer and a PO171 code appear. Replaced a sensor as recommended at the dealer (seems like replace one by one until problem solved, for short doesnt know the prob). I dont have the money to do the step by step replacements. Have been reading info in the web about that particular code but cannot understand. Can somebody explain it in a laymans term and possible solutions. Thanks

2wd-K5

The MAF (Mass Air Flow) Sensor is dirty or faulty. Note: The use of "oiled" air filters may cause the MAF to become dirty if the filter is over-oiled. There is also an issue with some vehicles where the MAF sensors leak the silicone potting material used to protect the circuitry.
There could be a vacuum leak downstream of the MAF sensor.
In the vast majority of cases, simply cleaning the MAF sensor does the trick. Consult your service manual for it's location if you need help. I find it's best to take it off and spray it with electronics cleaner or brake cleaner. Make sure you are careful not to damage the MAF sensor, and make sure it's dry before reinstalling
Inspect all vacuum and PCV hoses, replace if necessary
Check for a dirty fuel filter and proper fuel pressure

In the vast majority of cases, simply cleaning the MAF sensor does the trick. Consult your service manual for it's location if you need help. I find it's best to take it off and spray it with electronics cleaner or brake cleaner. Make sure you are careful not to damage the MAF sensor, and make sure it's dry before reinstalling
Inspect all vacuum and PCV hoses, replace if necessary
Check for a dirty fuel filter and proper fuel pressure

Melvin

Hi 2wd-K5, I started this morning first step (cleaning the MAF sensor). I bought the electrical cleaner and a new air filter. Read some articles to locate the MAF sensor and how to clean it. When I pull out the MAF sensor everything seems to be clean but when I used a flashlight looking inside I saw a debri, its like a pollen( from the grass I think) that you can see flying all over during summer. I got it out and sprayed the cleaner. Change the air filter and clean the air hose. When I put everything back and started the engine. check engine light was OFF and the idle is smooth now. I guess that solve the prob. Thanks a lot for your advice. Will still continue on the rest of cleanning (feul filter and PCV hoses).

cpick13

Have replaced MAF sensor on 2006 Chevy Trailblazer, Inline 4.2L, with 260,000+ miles, service engine soon light remains lit. Went off briefly when plugs were changed and then again when sensor was replaced. But back on now. HELP!!!! Code PO171