Changed my spark plugs last night (created a how to post on it) and today I got a check engine light. After gettin home tonight and running a diagnostic with my OBD II scanner it revealed a P0171 System To Lean (Bank 1), Big Props ROBO on your tech data!!!
So perhaps I have a lose vacum hose? Thats better than hearing I have the 06 Head Curse! Either way its nice that I can isolate this to occurring after the plugs were changed, so then something changed at that point!!!!
Also found this to be helpfull!
This information applies to the 2004-06 Chevrolet Colorado, GMC Canyon and 2006 Hummer H3.
On rare occasions, a SES light may be experienced with a P0171 and no engine performance concerns. Low MAF sensor grams and excessive long term fuel trim may be noted at a hot idle.
If the SI diagnostics do not isolate a concern, the following information may help.
1. Inspect the AIR intake system for rolled connections, cracks, or loose clamps between the MAF sensor and throttle body and repair.
2. If the long term fuel trim is consistently over 10% during an extended hot idle, temporarily plug the PCV vacuum pipe at the left rear of the cam cover, reset the fuel trims and note the long term fuel trim again after an extended hot idle.
If the fuel trim stays below 10%, the PCV system may be drawing in un-metered fresh air through:
- the cam cover
- air intake snorkel
- air cleaner resonator
- PCV dirty air hose rubber connector
- PCV fresh air hose
Inspect all of these areas for concern and repair as necessary.
3. If this concern was not present before the air cleaner resonator (on top of the cam cover) was removed during recent repairs, the PCV fresh air hose may not be fully seated to the tube on the right rear of cam cover or to the air cleaner resonator.
If this concern was not present before the cam cover was removed for internal engine repairs and there is no problem found on step 2, there may be a cam cover or cam cover gasket concern.
4. If the long term fuel trim stays above 10% with the PCV vacuum pipe plugged, temporarily remove the air filter element, reset the fuel trims and evaluate the fuel trim after an extended hot idle. If the fuel trim remains around 0% with the air filter element removed, there is an issue with the air filter that is causing lower than normal MAF readings. Replace the air filter and evaluate the concern.
5. If none of the above helps, inspect the throttle body gasket. If it is mispositioned, it may cause an intermittent vacuum leak.
TIP:Â Any of the above items can cause unmetered air to enter the engine, resulting in a lean concern and a P0171 DTC.
- Thanks to Jamie Parkhurst
2006 Red H3 Base w/Chrome & sunroof. 54k miles! Upgrades: Front tint, mud flaps, roof racks, custom rear tire cover, Poly cross-member bushing replacement (still strategizing). Soon to come: Clear corner lights, brush guard, front level w/Bliestien shocks and bump stops. PCMpluss computer upgrade