P0156

H : DTC P0156, P0158, P0161

H1: CHECK THE VOLTAGE AND SIGNAL GROUND SUPPLY TO THE CATALYST MONITOR SENSOR
1. Switch the ignition switch to the OFF position.
2. Raise and support the vehicle.
3. Disconnect the left hand catalyst monitor sensor electrical connector GB4.
4. Switch the ignition switch to the RUN position.
5. Measure the voltage between the left hand catalyst monitor sensor electrical connector GB4 pin 1, (GB)and pin 3 (NG).

Is the voltage greater than 10.5 volts?

Yes
Go to H3

No
Go to H2

H2: CHECK THE CATALYST MONITOR SENSOR VOLTAGE SUPPLY CIRCUIT
1. Measure the voltage between the left hand catalyst monitor sensor electrical connector GB4 pin 1, (GB) and ground.

Is the voltage greater than 10.5 volts?

Yes
REPAIR the circuit between the left hand catalyst monitor sensor electrical connector GB4 pin 2, (BG) and the spliced joint GB53. CLEAR DTC. TEST the system for normal operation.

No
REPAIR the circuit between the left hand catalyst monitor sensor electrical connector GB4 pin 1, (GB) and the spliced joint GBS1. CLEAR DTC. TEST the system for normal operation.

H3: CHECK THE CATALYST MONITOR SENSOR HEATER CONTINUITY
1. Switch the ignition switch to the OFF position.
2. Measure the resistance between the left hand catalyst monitor sensor electrical connector GB4 pin 1, (GB) and pin 2 (BG).

Is the resistance between 3 and 10 ohms?

Yes
Go to H4

No
INSTALL a new left hand catalyst monitor sensor. CLEAR DTC. TEST the system for normal operation.

H4: CHECK THE CATALYST MONITOR SENSOR FOR FAILURE
1. Connect the left hand catalyst monitor sensor electrical connector GB4.
2. RUN the engine until the catalyst monitor sensor has warmed up and maintain a speed of approximately 2500 rpm.
3. Disconnect the left hand catalyst monitor sensor electrical connector GB4.
4. Measure the voltage between the left hand catalyst monitor sensor electrical connector GB4 pin 3, (NG) and pin 4 (WG).

Is the voltage between 600 mV and 1.0 Volt?

Yes
Go to H5

No
INSTALL a new left hand catalyst monitor sensor. CLEAR DTC. TEST the system for normal operation.

H5: CHECK THE CATALYST MONITOR SENSOR FOR FAILURE
1. Connect the left hand catalyst monitor sensor electrical connector GB4.
2. REDUCE the engine speed to idle.
3. Disconnect the left hand catalyst monitor sensor electrical connector GB4.
4. Measure the voltage between the left hand catalyst monitor sensor electrical connector GB4 pin 3, (NG) and pin 4 (WG).

Has the voltage dropped to less than 400 mV?

Yes
Go to H6

No
INSTALL a new left hand catalyst monitor sensor. CLEAR DTC. TEST the system for normal operation.

H6: CHECK THE CATALYST MONITOR SENSOR FOR FAILURE
1. Connect the catalyst monitor sensor electrical connector GB4.
2. INCREASE the engine speed to approximately 2500 rpm.
3. Disconnect the catalyst monitor sensor electrical connector GB4.

Has the voltage Increased to between 600 mV to 1.0 Volt?

Yes
Go to H7

No
INSTALL a new catalyst monitor sensor. CLEAR DTC. TEST the system for normal operation.

H7: CHECK THE CATALYST MONITOR SENSOR FOR SHORT TO GROUND
1. Switch the ignition switch to the OFF position.
2. Measure the resistance between the catalyst monitor sensor electrical connector GB4 pin 1, (GB) and the monitor sensor body, and between the catalyst monitor sensor electrical connector GB4 pin 3, (NG) and the monitor sensor body.

Is the resistance greater than 10 M ohms?

Yes
Go to H8

No
INSTALL a new catalyst monitor sensor. CLEAR DTC. TEST the system for normal operation.

H8: CHECK THE CATALYST MONITOR SENSOR SIGNAL GROUND CIRCUIT FOR OPEN
1. Measure the resistance between the catalyst monitor sensor electrical connector GB4 pin 3, (NG) and ground.

Is the resistance greater than 10,000 ohms?

Yes
REPAIR the circuit between the catalyst monitor sensor electrical connector GB4 pin 3, (NG) and the spliced joint GB53. CLEAR DTC. TEST the system for normal operation.

No
Go to H9

H9: CHECK THE CATALYST MONITOR SENSOR CIRCUIT FOR OPEN
1. Remove the powertrain control module (PCM).
2. Measure the resistance between the catalyst monitor sensor electrical connector GB4 pin 4, (WG) and the powertrain control module electrical connector GB1 pin 29, (WG).

Is the resistance greater than 10,000 ohms?

Yes
REPAIR the circuit between the catalyst monitor sensor electrical connector GB4 pin 4, (WG) and the powertrain control module electrical connector GB1 pin 29, (WG). INSTALL the powertrain control module (PCM). CLEAR DTC. TEST the system for normal operation.

No
Go to H10

H10: CHECK THE CATALYST MONITOR SENSOR CIRCUIT FOR SHORT TO GROUND
1. Measure the resistance between the catalyst monitor sensor electrical connector GB4 pin 4, (WG) and ground.

Is the resistance less than 10,000 ohms?

Yes
REPAIR the input circuit between the catalyst monitor sensor electrical connector GB4 pin 4, (WG) and the powertrain control module electrical connector GB1 pin 29, (WG). INSTALL the powertrain control module (PCM). CLEAR DTC. TEST the system for normal operation.

No
Go to H11

H11: CHECK THE CATALYST MONITOR SENSOR HEATER CIRCUIT FOR OPEN
1. Measure the resistance between the catalyst monitor sensor electrical connector GB4 pin 2, (BG) and the powertrain control module electrical connector GB1 pin 16, (BG).

Is the resistance greater than 10,000 ohms?

Yes
REPAIR the output circuit between the catalyst monitor sensor electrical connector GB4 pin 2, (BG) and the powertrain control module electrical connector GB1 pin 16, (BG). INSTALL the powertrain control module (PCM). CLEAR DTC. TEST the system for normal operation.

No
Go to H12

H12: CHECK THE OXYGEN SENSOR HEATER CIRCUIT FOR SHORT TO GROUND
1. Measure the resistance between the catalyst monitor sensor electrical connector GB4 pin 2, (BG) and ground.

Is the resistance less than 10,000 ohms?

Yes
REPAIR the output circuit between the catalyst monitor sensor electrical connector GB4 pin 2, (BG) and the powertrain control module electrical connector GB1 pin 16, (BG). INSTALL the powertrain control module (PCM). CLEAR DTC. TEST the system for normal operation.

No
Go to H13

H13: CHECK THE CATALYST MONITOR SENSOR SIGNAL GROUND CIRCUIT FOR SHORT TO GROUND
1. Disconnect both catalyst monitor sensor electrical connectors GB3, GB4.
2. Measure the resistance between the catalyst monitor sensor electrical connector GB4 pin 3, (NG) and ground.

Is the resistance less than 10,000 ohms?

Yes
REPAIR the signal ground circuit between the catalyst monitor sensor electrical connector GB4 pin 3, (NG) and the spliced joint GBS3. INSTALL the powertrain control module (PCM). CLEAR DTC. TEST the system for normal operation.

No
INSTALL a new powertrain control module (PCM). CLEAR DTC. TEST the system for normal operation.