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.
P0174-Fuel System 2/1 Lean Control Below Limit (At Load): Notes
- When Monitored : With the engine running in closed loop mode, the ambient/battery temperature above -7°C (20°F), altitude below 2590m (8500 ft). and fuel level greater than 15%.
- Set Condition : If the PCM multiplies short term compensation by long term adaptive and a certain percentage is exceeded for two trips, the MIL illuminates and a trouble code is stored.
| Possible Causes |
|---|
| RESTRICTED FUEL SUPPLY LINE |
| FUEL PUMP INLET STRAINER PLUGGED |
| O2 SENSOR SIGNAL CIRCUIT |
| O2 SENSOR GROUND CIRCUIT |
| O2 SENSOR HEATER OPERATION |
| MANIFOLD ABSOLUTE PRESSURE SENSOR OPERATION |
| ENGINE COOLANT TEMPERATURE SENSOR OPERATION |
| ENGINE MECHANICAL PROBLEM |
| O2 SENSOR |
| FUEL PUMP |
| FUEL CONTAMINATION/EXHAUST LEAK |
For a complete Powertrain Control Module Circuit Diagram, refer to SCHEMATICS AND DIAGRAMS .
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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.
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