DTC 45

Code 45 "Oxygen Sensor Circuit":

Wiring Diagram - Oxygen Sensor Circuit:

CODE 45

OXYGEN SENSOR CIRCUIT (RICH EXHAUST INDICATED)


Circuit Description:

Code 45 indicates that the ECM has seen:

High oxygen sensor voltage

More than specified time (about 2 minutes)

Within a specified TPS voltage range (part throttle)

In "Closed Loop"

A high voltage can be caused by a rich exhaust or 02 sensor contaminated with silicone.


Test Description: Numbers below refer to circled numbers on the diagnostic chart.

1. System will go "Open Loop" if 02 sensor cools off while idling engine. Scan "Loop" status often during test.

2. This step causes a lean condition by putting an air leak into the engine to see if ECM can respond. A drop in the dwell indicates ECM and 02 sensor are not faulty. Look for source of constant rich condition.


3. This step tests to see if ECM is able to respond to a lean exhaust 02 signal (low voltage). If no dwell change, with a grounded lead to 02 sensor terminal "9" the fault is in ECM. It couldn't be an open 02 CKT 412 because that would set Code 13.

4. The system's response in step 2, indicates the exhaust is actually rich. This could be due to wires at M/C solenoid connected backwards, or excessive fuel into engine.