DTC P0171 Or DTC P0172: Condition

DTC P0171 is set when Engine Control Module (ECM) detects that total fuel trim is more than 33 percent. DTC P0172 is set when ECM detects that total fuel trim is less than -33 percent. MIL is illuminated when ECM detects malfunction during 2 consecutive drive cycles. Possible causes are:

• Vacuum leaks.
• Exhaust system leaks.
• Incorrect fuel pressure.
• Fuel injector malfunction.
• HO2S No. 1 malfunction.
• Mass Air Flow (MAF) sensor malfunction.
• ECM malfunction.
• Fuel level sensor malfunction.