Hi!,this day. In this posting you will find a description of fuses and relays Error P0138 – how to fix?
Include with photos of block diagrams along with their locations. Highlighted the cigarette lighter fuse (as typically the most popular thing people look for).
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Code Definition P0138
O2 High Voltage Sensor Circuit (Bank 1, Sensor 2)
What does the code P0138 mean
P0138 is a generic OBD-II code which indicates that the O2 sensor in Bank 1, Sensor 2 has no output voltage below 1.2V for more than 10 seconds, indicating no oxygen in the exhaust stream.
What causes the code P0138?
- The engine control module (ECM) sees the O2 sensor voltage for sensor bank 1 above 1.2 volts when the ECM has commanded fuel to a target lean state on that engine bank.
- The ECM detects a high voltage problem and turns on the Check Engine light.
- The ECM uses other O2 sensors to try to control fuel injection with their values.
What are the symptoms of the P0138 code?
- The engine may be idling during the sensor test to correct the problem, and may fail or stall.
- The Check Engine indicator light will come on.
- Engine running problems may occur depending on the cause of the rich state fault.
How does the mechanic diagnose the P0138 code?
- Scan the codes and document the data from the frozen frame, then erase the codes to verify the fault.
- Monitor the O2 sensor data to see if the voltage is changing between low and high at a rapid rate compared to other sensors.
- Check the O2 sensor wiring and harness connections for corrosion at the connections.
- Check the O2 sensor for physical damage and fluid contamination.
- Check for exhaust gas leaks upstream of the sensor.
- For further diagnostics, spot tests recommended by the manufacturer should be performed.
The most common errors when diagnosing the P0138 code
- Follow these simple tips to avoid misdiagnosis:
- The O2 sensor 1 for bank 1 can be used to diagnose the O2 sensor 2 for bank 1 by looking at the operation of both sensors for comparison. Operation should be about the same, except sensor 2 should have a lower O2 reading because the catalytic converter has to burn off the excess fuel and oxygen.
- Check the O2 sensor for oil or coolant contamination from possible engine leaks.
- Check that the catalytic converter is not damaged or is not clogged, which could cause erroneous sensor readings.
How serious is the P0138 code?
- The O2 sensor output voltage may be caused by a faulty exhaust gas catalytic converter which may cause the high output voltage of the O2 sensors.
- The ECM may not properly control the fuel-to-air ratio of the engine, resulting in a clogged catalytic converter and excessive carbon build-up in an engine with dirty spark plugs.
What repairs can fix the code P0138?
- Replacing the O2 sensor in bank 1 of sensor 2.
- Repair or replace wiring or connection to O2 sensor for bank 1 of sensor 2.
- Replace the catalytic converter upstream of the sensor
- Repair the leaking injector
Additional notes regarding the P0138 code
The O2 sensor high voltage status indicates a lack of oxygen in the exhaust gas or other related problems such as a leaking fuel injector or a damaged catalytic converter inside.