Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
DTC P0171-A: 1/1 Fuel System Lean
1999 Chrysler LHSSECTION DTC P0171-A: 1/1 Fuel System Lean
NOTE:
For connector terminal ID, see CONNECTOR IDENTIFICATION . For wiring diagram, see
WIRING DIAGRAMS article.
- For fuel system identification, see 1/1 FUEL SYSTEM IDENTIFICATION table. Using scan tool, read DTCs. If Global Good Trip displayed is zero, go to next step. If Global Good Trip displayed is not zero, go to step 6.1/1 FUEL SYSTEM IDENTIFICATION
Application Location Concorde, Intrepid, LHS & 300M Right Bank Upstream O2S - 1/1 FUEL SYSTEM LEAN DTC sets when the Powertrain Control Module (PCM) performs a test to determine if fuel system is running too lean. The PCM will compensate for variations in engine specifications, sensor tolerances and engine wear over the life of the engine. If PCM cannot compensate for engine or operating variations, the Malfunction Indicator Light (MIL) will illuminate. Possible causes are: faulty ignition coil, failed PCM, engine parts tolerance, leaking exhaust pipe/manifold, faulty fuel pump, plugged fuel filter, faulty secondary ignition cables, low fuel level, injectors stuck closed, faulty Manifold Absolute Pressure (MAP) sensor, faulty upstream O2S, faulty fuel pressure regulator, faulty fuel pump relay, faulty spark plugs, pinched fuel line, faulty wiring or connectors. Go to next step.
- Using scan tool, read trouble codes. Repair any other Diagnostic Trouble Codes (DTCs) before proceeding with this test. If no other DTCs are set, check for any Technical Service Bulletins (TSB) which may apply. If any TSBs are found to apply, perform TSB action as necessary. If no TSBs apply, go to next step.
- Perform fuel delivery test. See TEST NTC-5A: ROAD TEST FOR OBD-II TROUBLE CODES . If TEST NTC-5A passed, go to next step. If TEST NTC-5A did not pass, repair as necessary under NTC-5A. Test is complete. Perform TEST VER-5A: ROAD TEST FOR OBD-II TROUBLE CODES .
- Start engine. Using scan tool, read ADAPTIVE MEMORY FACTOR. If adaptive memory factor is more than +44 percent, perform DTC P0171-B: 1/1 FUEL SYSTEM LEAN . If adaptive memory factor is not more than +44 percent, test is complete. Perform TEST VER-5A: ROAD TEST FOR OBD-II TROUBLE CODES .
- Condition to set trouble code is not present at this time. Using scan tool, read FREEZE FRAME data. Use this information for additional diagnostics. Try to duplicate engine operating conditions. Pay particular attention to Engine Coolant Temperature (ECT) and engine RPM. Test is complete. Perform TEST VER-5A: ROAD TEST FOR OBD-II TROUBLE CODES .
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.