P0138 high circuit malfunction
- Thread starter Akingkhan
- Start date
DTC P0138: Secondary HO(2)S (Sensor 2) Circuit High Voltage - Except F23A4 SULEV engine
Reset the ECM/PCM.
Start the engine. Hold the engine at 3,000 rpm with no load (in Park or neutral) until the radiator fan comes on.
Check the Secondary HO(2)S (Sensor 2) output voltage at 3,000 rpm with the scan tool. Does the voltage stay at 0.6 V or more? YES - Go to step 4. NO - Intermittent failure, system is OK at this time. Check for poor connections or loose wires at C204 (located under the right side of the dash), C102 (located under the under-hood fuse/relay box), the Secondary HO(2)S (Sensor 2), and the ECM/PCM.
Turn the ignition switch OFF.
Disconnect the Secondary HO(2)S (Sensor 2) 4P connector.
Connect Secondary HO(2)S (Sensor 2) 4P connector terminals No.1 and No.2 with a jumper wire.
Turn the ignition switch ON (II).
Check the Secondary HO(2)S (Sensor 2) output voltage with the scan tool. Is there 0.6 V or more? YES - Go to step 9. NO - Replace the Secondary HO(2)S (Sensor 2).
Turn the ignition switch OFF.
Connect ECM/PCM connector terminals A23 and C18 with a jumper wire.
Turn the ignition switch ON (II).
Check the Secondary HO(2)S (Sensor 2) output voltage with the scan tool. Is there 0.6 V or more? YES - Substitute a known-good ECM/PCM and recheck. If the symptom/indication goes away, replace the original ECM/PCM. NO - Repair open in the wire between the ECM/PCM (A23) and the Secondary HO(2)S (Sensor 2).
alldata instructions for problem solving this code
also do u have the a4? (sulev)
I love the Substitute known good PCM tip from alldata... like oh, is that all.
High signal, means you have high resistance on a wire or no continuity. I would make sure you didn't break a wire off the o2 when you installed the test pipe. You need to disconnect your ecu and test the continuity on the wires from the o2 to the ECU. Make sure the batt is disconnected too.
High signal, means you have high resistance on a wire or no continuity. I would make sure you didn't break a wire off the o2 when you installed the test pipe. You need to disconnect your ecu and test the continuity on the wires from the o2 to the ECU. Make sure the batt is disconnected too.
