DTC P0135: A/F Sensor (Sensor 1) Heater Circuit Malfunction

NOTE: Before you troubleshoot, record all freeze data and any on-board snapshot, and review the general troubleshooting information (see GENERAL TROUBLESHOOTING INFORMATION ).

Turn the ignition switch to ON (II).
Clear the DTC with the HDS.
Start the engine. Hold the engine speed at 3, 000 rpm without load (in P or N) until the radiator fan comes on, then let it idle.
Check for Pending or Confirmed DTCs with the HDS.
Is DTC P0135 indicated?

YES -Go to step 5.

NO -Intermittent failure, the system is OK at this time. Check for poor connections or loose terminals at the A/F sensor (Sensor 1), the A/F sensor relay, and the PCM.
Turn the ignition switch to LOCK (0).
Check the No. 26 A/F SENSOR (10A) fuse in the under-dash fuse/relay box.
Is the fuse OK?

YES -Go to step 7.

NO -Go to step 20.
Open the fuse access panel (A), then remove the A/F sensor relay (B) from the under-dash fuse/relay box.

Fig 1: Identifying Fuse Access Panel And A/F Sensor Relay
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Test the A/F sensor relay (see POWER RELAY TEST ).
Is the A/F sensor relay OK?

YES -Go to step 9.

NO -Replace the A/F sensor relay, then go to step 24.
Disconnect the A/F sensor (Sensor 1) 4P connector.
At the sensor side, measure the resistance between A/F sensor (Sensor 1) 4P connector terminals No. 3 and No. 4.

Fig 2: Measuring Resistance Between A/F Sensor (Sensor 1) 4P Connector Terminals No. 3 And No. 4
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there 2.0-2.4 Ω at room temperature (65-70°F, 18-21°C)?

YES -Go to step 11.

NO -Go to step 23.
At the sensor side, check for continuity between A/F sensor (Sensor 1) 4P connector terminals No. 2 and No. 3, and between terminals No. 2 and No. 4 individually.

Fig 3: Checking Continuity Between A/F Sensor (Sensor 1) 4P Connector Terminals No. 2 And No. 3
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES -Go to step 23.

NO -Go to step 12.
Jump the SCS line with the HDS.
Disconnect PCM connector C (49P).
Check for continuity between PCM connector terminal C9 and A/F sensor (Sensor 1) 4P connector terminal No. 3.

Fig 4: Checking Continuity Between PCM Connector Terminal C9 And A/F Sensor (Sensor 1) 4P Connector Terminal No. 3
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES -Go to step 15.

NO -Repair an open in the wire between the PCM (C9) and the A/F sensor (Sensor 1), then go to step 24.
Connect A/F sensor (Sensor 1) 4P connector terminal No. 4 to body ground with a jumper wire.

Fig 5: Connecting A/F Sensor (Sensor 1) 4P Connector Terminal No. 4 To Body Ground Using Jumper Wire
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Check for continuity between A/F sensor relay 4P connector terminal No. 1 and body ground.

Fig 6: Checking Continuity Between A/F Sensor Relay 4P Connector Terminal No. 1 And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES -Go to step 17.

NO -Repair an open in the wire between the A/F sensor (Sensor 1) and the A/F sensor relay, then go to step 24.
Disconnect PCM connector A (49P).
Connect PCM connector terminal A49 to body ground with a jumper wire.

Fig 7: Connecting PCM Connector Terminal A49 To Body Ground Using Jumper Wire
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Check for continuity between A/F sensor relay 4P connector terminal No. 3 and body ground.

Fig 8: Checking Continuity Between A/F Sensor Relay 4P Connector Terminal No. 3 And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES -Go to step 30.

NO -Repair an open in the wire between the PCM (A49) and the A/F sensor relay, then go to step 24.
Open the fuse access panel (A), then remove the A/F sensor relay (B) from the under-dash fuse/relay box.

Fig 9: Identifying Fuse Access Panel And A/F Sensor Relay
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Disconnect the A/F sensor (Sensor 1) 4P connector and the EVAP canister vent shut valve 2P connector.
Check for continuity between A/F sensor (Sensor 1) 4P connector terminal No. 4 and body ground.

Fig 10: Checking Continuity Between A/F Sensor (Sensor 1) 4P Connector Terminal No. 4 And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES -Repair a short in the wire between the A/F sensor relay, the A/F sensor (Sensor 1), and the EVAP canister vent shut valve. Also replace the No. 26 A/F SENSOR (10 A) fuse, then go to step 24.

NO -Replace the under-dash fuse/relay box (USA model) (see REMOVAL AND INSTALLATION ), (Canada model) (see CANADA MODEL ), then go to step 24.
Replace the A/F sensor (Sensor 1) (see A/F SENSOR REPLACEMENT ).
Reconnect all connectors.
Turn the ignition switch to ON (II).
Reset the PCM with the HDS.
Do the PCM idle learn procedure (see PCM IDLE LEARN PROCEDURE ).
Check for Pending or Confirmed DTCs with the HDS.
Is DTC P0135 indicated?

YES -Check for poor connections or loose terminals at the A/F sensor (Sensor 1), the A/F sensor relay, and the PCM, then go to step 1.

NO -Go to step 29.
Monitor the OBD STATUS for DTC P0135 in the DTCs MENU with the HDS.
Does the HDS indicate PASSED?

YES -Troubleshooting is complete. If any other Pending or Confirmed DTCs were indicated in step 28, go to the indicated DTC'S TROUBLESHOOTING .

NO -If the HDS indicates FAILED, check for poor connections or loose terminals at the A/F sensor (Sensor 1), the A/F sensor relay, and the PCM, then go to step 1. If the HDS indicates NOT COMPLETED, keep idling until a result comes on.
Reconnect all connectors.
Update the PCM if it does not have the latest software (see PCM UPDATE ), or substitute a known-good PCM (see SUBSTITUTING THE PCM ).
Start the engine.
Check for Pending or Confirmed DTCs with the HDS.
Is DTC P0135 indicated?

YES -Check for poor connections or loose terminals at the A/F sensor (Sensor 1), the A/F sensor relay, and the PCM. If the PCM was updated, substitute a known-good PCM (see SUBSTITUTING THE PCM ), then go to step 32. If the PCM was substituted, go to step 1.

NO -Go to step 34.
Monitor the OBD STATUS for DTC P0135 in the DTCs MENU with the HDS.
Does the HDS indicate PASSED?

YES -If the PCM was updated, troubleshooting is complete. If the PCM was substituted, replace the original PCM (see PCM REPLACEMENT ). If any other Pending or Confirmed DTCs were indicated in step 33, go to the indicated DTC'S TROUBLESHOOTING .

NO -If the HDS indicates FAILED, check for poor connections or loose terminals at the A/F sensor (Sensor 1), the PGM-FI subrelay, and the PCM. If the PCM was updated, substitute a known-good PCM (see SUBSTITUTING THE PCM ), then go to step 32. If the PCM was substituted, go to step 1. If the HDS indicates NOT COMPLETED, keep idling until a result comes on.