DTC 45

Fig. 012 - WIRING DIAGRAM for Code 45 Rich Exhaust Indication. VIN 3, VIN 9:

CODE 45, RICH EXHAUST INDICATION

The ECM supplies a voltage of about .45 volt between terminals "D6" and "D7". (If measured with a 10 megohm digital voltmeter, this may read as low as .32 volts) The O2 sensor varies the voltage within a range of about 1 volt if the exhaust is rich, down through about .10 volt if exhaust is lean.
The sensor is like an open circuit and produces no voltage when it is below about 360°C (600°F). An open sensor circuit or cold sensor causes open loop operation.
Code 45 is set when the O2 signal voltage at the ECM connector terminal "D7":
a. Remains above .7 volts for 2 minutes; and
b. Engine time after start 2 minutes or more.

Fig. 011 - Chart - Code 45 Rich Exhaust Indication:

1. Grounding the diagnostic terminal with the engine running, enables the "Field Service Mode" and allows the ECM to confirm either open or closed loop operation using the "SERVICE ENGINE SOON" light.
2. A steady light or open loop indicates the fault is present. Grounding CKT 412 causes a low O2 signal voltage. If the ECM and wiring are OK, The ECM should recognize the low voltage and confirm the lean signal by turning off the "SERVICE ENGINE SOON" light for at least 15 seconds.
3. A Code 45 will not be caused by a faulty O2 sensor. Code 45 indicates a rich exhaust and diagnosis should begin with the items listed.