DTC 45

Code 45 Chart:

Code 45 Wiring Diagram:

CIRCUIT DESCRIPTION:


The ECM supplies a voltage of about 0.45 volt between terminals "GE14" and "GE15." (If measured with a 10 megohm digital voltmeter, this may read as low as 0.32 volt.) The 02 sensor varies the voltage within a range of about 1 volt if the exhaust is rich, down through about 0.10 volt if exhaust is lean.

The sensor is like an open circuit and produces no voltage when it is below 316~C (600~F). An open sensor circuit or cold sensor causes "Open Loop" operation.


NOTE: Because of all the possible color code combinations used on electrical wiring diagrams, always refer to ECM CONNECTOR IDENTIFICATION under ELECTRICAL AND ELECTRONIC WIRING DIAGRAMS for correct color code identification of circuit.

TEST DESCRIPTION: Numbers below refer to circled numbers on the diagnostic chart.

1. Code 45 is set when:

^ 02 voltage is above 0.75 volt
^ No Code 33 or 34
^ Fuel system in "Closed Loop"
^ TPS above 5%
^ Above conditions met for 50 seconds


DIAGNOSTIC AIDS:

The Code 45 or rich exhaust is most likely caused by one of the following:

^ Fuel Pressure - System will go rich if pressure is too high. The ECM can compensate for some increase. However, if it gets too high, a Code 45 will be set. See CHART A-7.

^ Leaking Injector See CHART A-7.

^ HEI Shielding - An open ground CKT 453 may result in EMI or induced electrical noise. The ECM looks at this noise as distributor pulses. The additional pulses result in a higher than actual engine speed signal. The ECM then delivers too much fuel causing system to go rich.


^ Engine tachometer will also show higher than actual engine speed which can help in diagnosing this problem.


^ Canister Purge - Check for fuel saturation. If full of fuel, check canister control and hoses.

^ MAP Sensor - An output that causes the ECM to sense a higher than normal manifold pressure (low vacuum) can cause the system to go rich. Disconnecting the MAP sensor will allow the ECM to set a fixed value for the MAP sensor. Substitute a different MAP sensor if the rich condition is gone while the sensor is disconnected.

^ Pressure Regulator - Check for leaking fuel pressure regulator diaphragm by checking for the presence of liquid fuel in the vacuum line to the regulator.

^ TPS - An intermittent TPS output will cause the system to go rich due to a false indication of the engine accelerating.

^ 02 Sensor Contamination - Inspect oxygen sensor for silicone 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 surge driveability problem.