SES Light Due to a P0171 - Inspect for Air Leak or Air Filter Concern - keywords after cam CEL controls cover DTC engine element gas hose lamp leak low MAF MIL PCV repairs repeat

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

On rare occasions, a SES Light may be experienced with a P0171 and no engine performance concerns. Upon inspection, low MAF sensor grams and excessive long term fuel trims 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 as necessary.
2. If the LT Fuel Trim is consistently over 10% during an extended hot idle, temporarily plug the PCV vacuum pipe (Item 3) at the left rear of the cam cover, reset the fuel trims and note the LT Fuel Trim again after an extended hot idle. If the LT 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 (Item 1), PCV dirty air hose rubber connector (Item 2), or PCV fresh air hose (Item 6). 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 (Item 6) may not be fully seated to the tube on the right rear of cam cover (Item 4) or to the air cleaner resonator (Item 1). 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 LT Fuel Trim stays above 10% with the PCV vacuum pipe plugged, temporarily remove the air filter element, reset the fuel trims and evaluate the LT Fuel Trim after an extended hot idle. If the LT Fuel Trim remains around 0%, replace the air filter and evaluate the concern.
5. If none of the above helps, inspect the throttle body gasket to make sure that it is not mispositioned, which may cause an intermittent vacuum leak.

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.