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PO171 System Too Lean Diagnosis - 2002 Chevrolet Cavalier 2.2L Engine

Model: 2002 Chevrolet Cavalier Fault Code: P0171 Posted: 2007-07-18 12:06

2002 Chevrolet Cavalier with a 2.2L 4-cylinder engine, currently at 100,102 miles. My girlfriend's car just passed the 100,000-mile mark last week and suddenly stalled about one block from home. With only 1/8 of a tank of fuel remaining, I'm unable to get the engine to turn over—should I add more gas? I connected an OBD-II scanner and received only one diagnostic code: PO171 — System Too Lean. I've read various forums suggesting solutions such as cleaning the Mass Airflow (MAF) sensor, inspecting the oxygen sensors, replacing or cleaning air filters, and checking for intake leaks. However, as a non-mechanic, I'm hesitant to spend money on repairs without knowing what's actually wrong. Could this be caused by a failing fuel pump? Would that typically trigger another diagnostic code? Are there any steps I can take myself before taking it to a repair shop? I plan to pick up a Chilton manual today to locate the MAF sensor. Thanks for your insights.

Related fault codes
P0171
Comments (6)
Anonymous 2007-07-18 12:54

What fuel pump-related codes should you expect? A complete circuit failure in the fuel pump can result in no fuel pressure at all—even if the pump is running. If you're unsure whether fuel is reaching the rail, don't waste time on MAF or sensor cleaning. Remove the gas cap and cycle the ignition switch to 'Run' position without cranking—do you hear the fuel pump activate?

Anonymous 2007-07-18 13:34

The first step should be checking fuel pressure. Please post your results so we can assess further.

Anonymous 2007-07-19 11:20

Are you certain there's actually fuel in the tank? GM fuel sending units are well-known for inaccurate gauge readings. Try adding a few gallons of gas and attempt to start the vehicle. You cannot get any leaner than zero fuel. If it doesn't start, follow Darkrooms' advice and check fuel pressure. Best of luck—please update us on your progress.

Anonymous 2007-07-19 12:03

This was a perfect example of Occam's Razor: 'All things being equal, the simplest explanation is usually correct.' The fuel pump was running, which made me question why PO171 appeared—since this code typically affects idle and acceleration more than startup. I initially thought the code might be unrelated to starting. After purchasing MAF cleaner, fuel injector cleaner, and other sensor cleaning products, I decided to test for fuel presence using a 4-gallon gas can. The car had over 1/8 of a tank on the gauge with no warning light—yet there was clearly no fuel. After adding several pumps, the engine turned over successfully. The PO171 code remained but disappeared after a brief application of fuel injector cleaner and a light cleaning of the MAF sensor. I still took the car in for service as a precaution and because it had been overdue. Thank you Jeff Compton, Darkrooms, and MohawkMtrs for your helpful advice. Now I just need to fix the inaccurate gas gauge.

Anonymous 2007-07-19 13:30

It's been our pleasure!

Anonymous 2007-07-20 07:33