I have a 2001 GMC Sierra 5.3...I am getting engine code PO171. But the check engine light only comes on with that code when it is cold outside.Like zero to 25/30 degress. When it warms a little above that temp the light goes out. No matter if light is on or not truck seams to run fine.I need some guidence as what to check. Thankyou
You have an OBD Fault Code--diagnose it & resolve
You can Google the codes & read up (OBD PO171)
O2 Sensors get replaced every 100,000 miles as preventative
maintenance- so do the maint on the entire truck
When the motor is running & ANY Dash Light comes on, you
have a problem,get the codes the same day & decide of you got
a couple days before you need to make the repair or park it
With the engine cold spray the intake manifold near the gasket with the carb cleaner see if the idle changes if it does replace the gasket
SOURCE: Check engine light on after getting gas on Code
Check and clean gas cap "O" ring, and threads and mating surface in filler neck as well, and re-install cap tightly. If that doesn't take care of it, you may have a vacuum leak to the MAF (Mass Air flow) sensor, or a faulty or dirty MAF sensor, which can be sprayed with some success to clean it with electrical spray cleaner or tuner spray cleaner from electronics store.
Testimonial: "Thank you that was very helpful"
SOURCE: have this code PO171, what does this mean.
Not sure that the O2 sensor was bad. It sounds like it was telling you that side of the exhaust system was picking up a lean mixure at the O2 sensor. The O2 sensor was doing its job by telling you the mixture changed. If the O2 sensor was bad, it would say low voltage range for that sensor, or open curcuit.
Now the car has had time to do its diagnostic sweep, it is telling you the same thing, but from a different sensor...the fuel mix is too lean. Air/spark/and fuel is what you need in the correct amounts. In your car, the ECM engine control module controls this by taking readings from all the sensors several hundred times a second.
Mechanically, you have a few options. Change the fuel filter...under the car on the passenger side. It is an easy job.
Change the fuel pressure regulator. This keeps the fuel at 4 BAR so the fuel injectors can do their job correctly. This job just needs a screw driver to pop off the clip that holds it in place. No hoses need to be removed. It is on top of the intake manifold, in-line with a metal fuel line and a rubber one.
The fuel injectors could be clogged up on one side of the engine. Run some fuel injector cleaner through a tank of gas. Also, listen for a constant ticking sound at each injector. If one sounds off PAR, then replace it.
The fuel pump may not be giving you enough power. However, the readings seem to be localized to one side, so I doubt it.
Start with the easiest thing, and see if it works. Also, you will need to get yourself a VAG scan tool. It is the only one with codes in it for all of your VW systems, not just engine codes like the ODB scanners. You can get a nice one for $50 on-line.
Good Luck!
SOURCE: I have a 2006 Trailblazer. When it is cold
Code P0171 is a lean oxygen sensor code for bank 1 on your engine. Bank 1 is always the side of the engine where #1 cylider is located.
There are a couple of Technical Service Bulletins (TSB's) that may apply to your problem.
Bulletin No.: 09-06-03-004C
This bulletin covers intermittent problems due to oxidation problems in some of the wiring connectors.
Bulletin No.: 03-06-04-030G
This bulletin outlines repair proceedures for clogged or restricted fuel injectors.
The only other thing I can think of would be a vacuum leak that occurs only in cold ambient temperatures and only affects bank 1. (possible intake manifold gasket or something similar.)
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