## PGM-FI System

#### DTC Troubleshooting (cont'd)

11-252

DTC 41: Primary HO2S (Sensor 1) Heater Circuit Malfunction NOTE: Information marked with an asterisk (*) applies to D15Y2, D15Y4, D16W8, D17Z1, D17A2, D17Z3, D17Z4 engines.

1. Reset the ECM/PCM (see page 11-168).
2. Start the engine.

Is the MIL on and does it indicate DTC 41?

YES | - Go to step 3.
NO | - Intermittent failure, system is OK at this time. Check for poor connections or loose wires at the primary HO2S (Sensor 1) and at the ECM/PCM.

3. Turn the ignition switch OFF.
4. Disconnect the primary HO2S (Sensor 1) 4P connector.
5. At the primary HO2S side, measure resistance between the primary HO2S 4P connector terminals No. 3 and No. 4.

PRIMARY HO2S (SENSOR 1) 4P CONNECTOR

Terminal side of male terminals | Wire side of female terminals

Is there 10-40 ohms?

YES | - Go to step 6.
NO | - Replace the primary HO2S (Sensor 1).

6. Check for continuity between body ground and the primary HO2S 4P connector terminals No. 3 and No. 4 individually.

PRIMARY HO2S (SENSOR 1) 4P CONNECTOR

Terminal side of male terminals | Wire side of female terminals

Is there continuity?

YES | - Replace the primary HO2S (Sensor 1).
NO | - Go to step 7.

7. Turn the ignition switch ON (II).
8. Measure voltage between the primary HO2S (Sensor 1) 4P connector terminals No. 3 and No. 4.

PRIMARY HO2S (SENSOR 1) 4P CONNECTOR

Terminal side of male terminals | Wire side of female terminals

Is there battery voltage?

YES | - Go to step 9.
NO | - Go to step 12.

9. Turn the ignition switch OFF.
10. Disconnect ECM/PCM connector A (31P).