Mechanics

PONTIAC SUNBIRD SENSOR PROBLEM

1991 Pontiac Sunbird • 185,000 miles

I have codes 13, 23, and 44 showing for my 3.1l engine, I replaced the 02 sensor in the exhaust manifold and the code for that is still onhow do I fix these problems
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Murdawg1971
January 27, 2013.



Code 13

CIRCUIT DESCRIPTION: The Electronic Control Module (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 O2 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 SCHEMATIC DIAGRAMS/ELECTRICAL AND ELECTRONIC WIRING DIAGRAMS/ECM CONNECTOR IDENTIFICATION for correct color code identification of circuit.

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

Code 13 will set: Engine at normal operating temperature
At least 2 minutes engine time after start.
02 signal voltage steady between 0.35 and 0.55 volt.
Throttle position sensor signal above 4%.
All conditions must be met for about 120 seconds. If the conditions for a code 13 exist the system will not go "Closed Loop".

This will determine if the sensor is at fault or the wiring or ECM is the cause of the Code 13.
In doing this test use only a high impedance digital volt ohm meter. This test checks the continuity of CKTs 412 and 413 because if CKT 413 is open the ECM voltage on CKT 412 will be over 0.6 volt (600 mV).

DIAGNOSTIC AIDS: Normal "Scan" voltage varies between 100 mV to 999 mV (0.1 and 1.0 volt) while in "Closed Loop". Code 13 sets in one minute if voltage remains between 0.35 and 0.55 volt, but the system will go "Open Loop" in about 15 seconds. Refer to TESTING PROCEDURES/DIAGNOSIS BY SYMPTOM/INTERMITTENTS..

Code 23

CIRCUIT DESCRIPTION : The IAT sensor uses a thermistor to control the signal voltage at the ECM. The ECM applies a voltage (about 5 volts) on CKT 472 to the sensor. When the air is cold the sensor (thermistor) resistance is high, therefore the ECM terminal "GF16" voltage will be high. If the air is warm the sensor resistance is low, therefore the ECM terminal "GF16" voltage will be low.

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

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

Code 23 will set if: A signal voltage indicates a manifold air temperature below -35~C (31~F) for 10 seconds.
Time since engine start is 4 minutes or longer.
No VSS.

A Code 23 will set due to an open sensor, wire, or connection. This test will determine if the wiring and ECM are OK.
This will determine if the signal CKT 472 or the 5 volts return CKT 452 is open.

DIAGNOSTIC AIDS : A "Scan" tool displays temperature of the air entering the engine, which should be close to ambient air temperature when engine is cold, and rise as underhood temperature increases.
A faulty connection, or an open in CKT 472 or CKT 469 can result in a Code 23.
Codes 23 and 34 stored at the same time, could be the result of an open CKT 469. The "Temperature to Resistance Values" scale in the chart above may be used to test the IAT sensor at various temperature levels to evaluate the possibility of a "slewed" (mis-scaled) sensor. A "slewed" sensor could result in poor driveability complaints.
Refer to TESTING PROCEDURES/DIAGNOSIS BY SYMPTOM/INTERMITTENTS.

Code 44

CIRCUIT DESCRIPTION: The Electronic Control Module (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 about 316~C (600~F) An open sensor circuit or cold sensor causes "Open Loop" operation.

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

Code 44 is set when the 02 sensor signal voltage on CKT 412 remains below 0.2 volt for 6O seconds and the system is operating in "Closed Loop".

DIAGNOSTIC AIDS: Using the "Scan", observe the block learn values at different rpm and air flow conditions. The "Scan" also displays the block cells, so the block learn values can be checked in each of the cells to determine when the Code 44 may have been set. If the conditions for Code 44 exists the block learn values will be around 150.
02 Sensor Wire. Sensor pigtail may be mis-positioned and contacting the exhaust manifold. Check for intermittent ground in wire between connector and sensor.
Lean Injector(s). Perform injector balance test CHART C-2A.
Fuel Contamination. Water, even in small amounts, near the in-tank fuel pump inlet can be delivered to the injectors. The water causes a lean exhaust and can set a Code 44.
Fuel Pressure. System will be lean if pressure is too low. It may be necessary to monitor fuel pressure while driving the car at various road speeds and/or loads to confirm, See CHART A-7.
Exhaust Leaks. If there is an exhaust leak, the engine can cause outside air to be pulled into the exhaust and past the sensor. Vacuum or crankcase leaks can cause a lean condition.
If the above are OK, it is a faulty oxygen sensor.

These are the flow charts.

Roy

ASEMaster6371
Jan 27, 2013.