Page 1025 of 5267
P0152-O2 SENSOR 2/1 CIRCUIT HIGH
For a complete wiring diagramRefer to Section 8W.
Page 1026 of 5267

When Monitored:
With battery voltage greater than 10.4 volts, engine running for more than4 minutes and coolant temperature
above 180°F.
Set Condition:
The oxygen sensor voltage is above 1.5 volts.
Possible Causes
(K43) O2 2/1 SIGNAL CIRCUIT SHORTED TO VOLTAGE
(K199) O2 SENSOR 2/1 HEATER CONTROL CIRCUIT OPEN
(K43) O2 2/1 SIGNAL CIRCUIT OPEN
(K900) SENSOR GROUND CIRCUIT OPEN
(K343) ASD RELAY OUTPUT CIRCUIT OPEN
(K43) O2 2/1 SIGNAL CIRCUIT SHORTED TO THE (K343) ASD RELAY OUTPUT CIRCUIT
O2 SENSOR
PCM
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING).
Diagnostic Test
1.O2 SENSOR ABOVE 1.5 VOLTS
Ignition on, engine not running.
With the scan tool, read DTCs and record the related Freeze Frame data.
Start the engine.
Allow the engine to idle for 4 to 5 minutes.
With the scan tool, read the O2 Sensor voltage.
Is the voltage above 1.5 volts?
Ye s>>
Go To 2
No>>
Refer to the INTERMITTENT CONDITION Diagnostic Procedure.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
2.(K43) O2 2/1 SIGNAL CIRCUIT SHORTED TO VOLTAGE
Turn the ignition off.
Disconnect the C1 PCM harness connector.
Ignition on, engine not running.
Using a 12-volt test light connected to ground, probe the (K43) O2 Sen-
sor 2/1 Signal circuit at the 2/1 O2 Sensor harness connector.
Does the test light illuminate brightly?
Ye s>>
Repair the short to voltage in the (K43) O2 Sensor 2/1 Sig-
nal circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to
9 - ENGINE - STANDARD PROCEDURE)
No>>
Go To 3
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3.(K43) O2 SENSOR 2/1 SIGNAL CIRCUIT OPEN
Turn the ignition off.
Measure the resistance of the (K43) O2 Sensor 2/1 Signal circuit from
the O2 Sensor harness connector to the C1 PCM harness connector.
Is the resistance below 5.0 ohms?
Ye s>>
Go To 4
No>>
Repair the open in the (K43) O2 Sensor 2/1 Signal circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to
9 - ENGINE - STANDARD PROCEDURE)
4.(K43) O2 2/1 SENSOR SIGNAL CIRCUIT SHORTED TO THE (K343) ASD RELAY OUTPUT CIRCUIT
Measure the resistance between the (K43) O2 Sensor 2/1 Signal circuit
and the (K343) ASD Relay Output circuit at the O2 Sensor harness con-
nector.
Istheresistancebelow100ohms?
Ye s>>
Repair the short between the (K43) O2 Sensor 2/1 Signal
circuit and the (K343) ASD Relay Output circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to
9 - ENGINE - STANDARD PROCEDURE)
No>>
Go To 5
Page 1028 of 5267
5.(K900) SENSOR GROUND CIRCUIT OPEN
Measure the resistance of the (K900) Sensor ground circuit from the O2
Sensor harness connector to the C1 PCM harness connector.
Is the resistance below 5.0 ohms?
Ye s>>
Go To 6
No>>
Repair the open in the (K900) Sensor ground circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to
9 - ENGINE - STANDARD PROCEDURE)
6.(K343) ASD RELAY OUTPUT CIRCUIT OPEN
Connect the PCM harness connectors.
Ignition on, engine not running.
With the scan tool actuate the O2 Heater Test.
Using a 12-volt test light connected to ground, probe the (K343) ASD
Relay Output circuit.
Does the test light illuminate brightly?
Ye s>>
Go To 7
No>>
Repair the open in the (K343)ASD Relay Output circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to
9 - ENGINE - STANDARD PROCEDURE)
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7.(K199) O2 SENSOR 2/1 HEATER CONTROL CIRCUIT OPEN
Turn the ignition off.
Disconnect the C3 PCM harness connector.
Measure the resistance of the (K199) O2 Sensor 2/1 Heater Control cir-
cuit from the O2 Sensor harness connector to the PCM harness con-
nector.
Is the resistance below 5.0 ohms?
Ye s>>
Go To 8
No>>
Repair the open in the (K199) O2 Sensor 2/1 Heater Con-
trol Circuit (PWM) circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to
9 - ENGINE - STANDARD PROCEDURE)
8.PCM
NOTE: Before continuing, check the PCM harness connector terminals for corrosion, damage, or terminal
push out. Repair as necessary.
Using the schematics as a guide, inspect the wire harness and connectors. Pay particular attention to all Power and
Ground circuits.
Were there any problems found?
Ye s>>
Repair as necessary.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
No>>
Replace and program the Powertrain Control Module per Service Information.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
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P0153-O2 SENSOR 2/1 SLOW RESPONSE
For a complete wiring diagramRefer to Section 8W.
Page 1031 of 5267

When Monitored:
With ECT greater than 147°F, after reaching a vehicle speed of 10 mph, and the throttle remaining open (off
idle) for 2 minutes, bring the vehicle to a stop and allow the engine to idle with the transmission in DRIVE.
Set Condition:
The oxygen sensor signal voltage is switching from below 0.27 of a volt to above 0.62 of a volt and back fewer
times than required.
Possible Causes
EXHAUST LEAK
(K43) O2 2/1 SIGNAL CIRCUIT
(K900) SENSOR GROUND CIRCUIT
O2 SENSOR
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING).
Diagnostic Test
1.ACTIVE DTC
NOTE: Check for contaminants that may have damaged the O2 Sensor: contaminated fuel, unapproved sil-
icone, oil and coolant.
Ignition on, engine not running.
NOTE: After the repairs have been made, verify proper O2 Sensor operation.If all the O2 Sensor voltage
readings have not returned to normal, follow the diagnostic procedure forthe remaining O2 Sensors.
With a scan tool, read DTCs and record the related Freeze Frame data.
Is the DTC active at this time?
Ye s>>
Go To 2
No>>
Refer to the INTERMITTENT CONDITION Diagnostic Procedure. (Refer to 9 - ENGINE - STANDARD
PROCEDURE)
2.EXHAUST LEAK
Start the engine.
Inspect the exhaust system for leaks between the engine and the O2 Sensors.
Are there any exhaust leaks?
Ye s>>
Repair or replace the leaking exhaust parts as necessary.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
No>>
Go To 3
3.(K43) O2 2/1 SIGNAL CIRCUIT VOLTAGE DROP
Turn the ignition off.
While backprobing, measure the voltage of the (K43) O2 Sensor 2/1 Signal circuit between the 2/1 O2 Sensor har-
ness connector and PCM harness connector.
NOTE: Make sure the voltmeter leads meet the terminals in the connector andthat there is good terminal to
wire connection and are connected for positive polarity.
Start the engine.
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Allow the engine to idle.
Is the voltage below 0.10 of a volt?
Ye s>>
Go To 4
No>>
Repair the excessive resistance in the (K43) O2 Sensor 2/1 Signal circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
4.(K900) SENSOR GROUND CIRCUIT VOLTAGE DROP
Turn the ignition off.
While backprobing, measure the voltage of the (K900) Sensor ground circuit between the O2 Sensor harness con-
nector and PCM harness connector.
NOTE: Make sure the voltmeter leads meet the terminals in the connector andthat there is good terminal to
wire connection.
NOTE: Make sure the voltmeter leads are connected for positive polarity
Start the engine.
Allow the engine to idle.
Is the voltage below 0.10 of a volt?
Ye s>>
Go To 5
No>>
Repair the excessive resistance in the (K900) Sensor ground circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
NOTE: Turn the ignition off before continuing.
5.O2 SENSOR
If there are no possible causes remaining, view repair.
Repair
Replace the O2 Sensor
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)