DTC 45

WIRING DIAGRAM:

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 about 1 minute; and
b. The system is operating in closed loop.

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 "CHECK ENGINE" light.
2. A steady light "on" 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 "CHECK ENGINE" light for at least 15 seconds.
3. Diagnostic Aids
a. Code 45 indicates a rich exhaust and diagnosis should begin with the items listed.
b. Leaking Injector(s). Symptoms will be similiar to high fuel pressure. Perform fuel system diagnosis (Chart A-7A).
c. Inspect Oxygen Sensor for silicon contamination from fuel, or use of improper RTV sealant. The sensor may have a white, powdery coating and result in a high but false signal voltage (rich exhaust indication). The ECM will then reduce the amount of fuel delivered to the engine, causing a severe driveability problem.
d. Canister Purge, Check for fuel saturation. If full of fuel, check canister control and hoses. Chart C-3.
e. MAF Sensor. An output that causes the ECM to sense a higher than normal air flow (high signal) can cause the system to go rich. Disconnecting the MAF sensor will allow the ECM to use a default value for the MAF sensor. Substitute a different MAF sensor if the rich condition is gone with the MAF sensor disconnected.
f. Check for leaking fuel pressure regulator diaphram by checking vacuum line to regulator for fuel.
g. TPS. An intermittent TPS output will cause the system to go rich, due to a false indication of the engine accelerating.
h. Perform injector balance test Chart C-2A.