DTC 45

Fig. 015 - Chart - Code 45 Rich Exhaust Indication:

Fig. 016 - WIRING DIAGRAM for Code 45 Rich Exhaust Indication. VIN 3, VIN 9, VIN L:

CODE 45

RICH EXHAUST INDICATION

3.8L "A" & "C" SERIES, 3.8L TURBO "E" & "G" SERIES

The ECM supplies a voltage of about .45 volt between terminals "D7 and D6". (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 sensor signal voltage at the ECM C-D connector terminal D-7
a. Remains above .7 volt for 30 seconds; and
b. Engine time after start is 1 minute or more.
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.

DIAGNOSTICS AIDS

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:
a. A silicon contaminated O2 sensor will cause a steady signal above .55 volts and set code 45.
b. 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 may be set.
a. Leaking fuel pressure regulator, leaking injector. See Chart A-7.
c. HEI Sheilding. 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.
d. Canister purge. Check for fuel saturation. If full of fuel, see Chart C-3.
e. MAF sensor. An output that causes the ECM to sense a higher than normal manifold air flow can cause the system to go rich. Disconnecting the MAF sensor will allow the ECM to set a fixed value for the MAF sensor. Substitute a different MAF sensor if the the rich condition is gone while the sensor is disconnected.
f. TPS. An intermittent TPS output will cause the system to go rich, due to a false indication of the engine accelerating.