Circuit Description

PCM monitors oxygen sensor signal voltage and adjusts fuel delivery based on signal voltage. A change made to fuel delivery is indicated by the long and short term fuel trim values. Ideal fuel trim value is about 128 (zero percent).

A fuel trim value of more than 128 indicates that PCM is adding fuel to compensate for a lean condition. A fuel trim value less than 128 indicates that PCM is reducing amount of fuel to compensate for rich condition. DTC will set if PCM detects an excessively lean condition.

Conditions for setting this DTC are as follows:

• Engine coolant temperature is 140-239°F (60-115°C).
• TP sensor angle is less than 80 percent.
• Vehicle speed is less than 70 MPH.
• Engine speed is 750-3400 RPM.
• MAP sensor is more than 28 kPa.
• BARO sensor is more than 70 kPa.
• IAT sensor is between -13°F and 239°F (-25°C and 115°C).
• No presence of Codes: P0106-P0108, P0112, P0113, P0117, P0118, P0121-P0123, P0125, P0131-P0134, P0300-P0304, P0325, P0335, P0341, P0342, P0401, P0502, P0503, P0506, P0507, P0601, P1133, P1406, P1441.
• Fuel trim index is more than 165.
• EVAP purge is not occurring.