DTC P0171 Or DTC P0172: Condition

DTC P0171 is set when Power Control Module (PCM) detects that total fuel trim is more than 43 percent. DTC P0172 is set when PCM detects that total fuel trim is less than -30 percent. MIL is illuminated when PCM detects malfunction during 2 consecutive drive cycles. Possible causes are:

• PCM malfunction.
• Intake system vacuum leaks.
• Exhaust system leaks.
• Incorrect fuel pressure.
• HO2S No. 1 malfunction.
• EGR system malfunction.
• Mass Air Flow (MAF) sensor malfunction.
• Engine Coolant Temperature (ECT) sensor malfunction.
• Fuel level sensor malfunction.
• Vacuum leaks.