Powertrain Controls - ECM/PCM

DTC 46 Chart:

Heated Oxygen Sensor Circuit:

CIRCUIT DESCRIPTION
The PCM controls front to rear cylinder bank fuel delivery separately based on their respective oxygen sensor signals. If the PCM detects too great a difference between the front to rear bank long term fuel trim values, it will illuminate the Malfunction Indicator Lamp (MIL) (Service Engine Soon).

DTC 46 WILL SET WHEN
Front bank long term fuel trim value differs from rear bank long term fuel trim by more than 15 counts for 10 minutes or longer.

ACTION TAKEN (PCM WILL DEFAULT TO)
With a current DTC 46 set, the PCM will illuminate the Malfunction Indicator Lamp (MIL) (Service Engine Soon).

DTC 46 WILL CLEAR WHEN
The fault no longer exists and the ignition switch is cycled "OFF" and "ON."

DTC CHART TEST DESCRIPTION
Number(s) below refer to circled number(s) on the diagnostic chart.

1. Check and repair other codes first.
2. Checking for other mechanical problems causing code to set.
3. The bank that is the farthest from the neutral value of 128 is the bank which is out of fuel control.

DIAGNOSTIC AIDS
- Lean or faulty injectors on one side of the engine.
- Cracked or fouled spark plugs.
- Exhaust or intake manifold leak.