## PGM-FI System

#### DTC Troubleshooting (cont'd)

11-63

DTC P0135: Primary HO2S (Sensor 1) Heater Circuit Malfunction

1. Reset the ECM (see page 11-4).

1. Start the engine.

   Is DTC P0135 indicated?

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.

1. Turn the ignition switch OFF.

1. Disconnect the primary HO2S (Sensor 1) 4P connector.

1. At the primary HO2S side, measure resistance 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

Is there 10 - 40 ohms?

YES - Go to step 6.

NO - Replace the primary HO2S (Sensor 1).

1. Check for continuity between body ground and the primary HO2S (Sensor 1) 4P connector terminals No. 3 and No. 4 individually.

PRIMARY HO2S (SENSOR 1) 4P CONNECTOR

Terminal side of male terminals

Is there continuity?

YES - Replace the primary HO2S (Sensor 1).

NO - Go to step 7.

1. Turn the ignition switch ON (II).

1. Measure voltage between the primary HO2S (Sensor 1) 4P connector terminal No. 3 and No. 4.

PRIMARY HO2S (SENSOR 1) 4P CONNECTOR

Wire side of female terminals

Is there battery voltage?

YES - Go to step 9.

NO - Go to step 12.

1. Turn the ignition switch OFF.

1. Disconnect ECM connector A (31P).

a a a