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P0136 is a diagnostic trouble code (DTC) for "O2 Sensor Circuit Malfunction (Bank 1, Sensor 2)". This can happen for multiple reasons and a mechanic needs to diagnose the specific cause for this code to be triggered in your situation. Our certified mobile mechanics can come to your home or office to perform the Check Engine Light diagnostic. Once we are able to diagnose the problem, you will be provided with an upfront quote for the recommended fix and receive $20.00 off as a credit towards the repair. All our repairs are backed by our 12-month / 12,000-mile warranty.
O2 Sensor Circuit Malfunction (Bank 1, Sensor 2)
P0136 is the OBD-II generic code indicating the downstream O2 sensor for bank 1 fails to meet the minimum and maximum voltage limits calibrated for the ECM to see.
The ECM monitors the O2 sensor’s highest and lowest voltages. This code occurs when the voltage limits are not within specifications programmed into the ECM.
The ECM detects a voltage problem and turns on the Check Engine Light.
The ECM uses other O2 sensors to try and control the fuel injection with known values.
There is an exhaust leak or catalyst failure in front of the sensor.
The engine may run excessively rich if the engine goes into open loop.
The engine may start to misfire if the spark plugs get fouled out over time.
The Check Engine Light will be illuminated.
You may have exhaust leaks or loss of power from a clogged or bad catalyst.
Scans codes and documents freeze frame data then clear codes to verify failure
Monitors O2 sensor data to see if the voltage is switching back and forth between low and high at a fast rate compared to other sensors
Checks the O2 sensor wiring and the harness connections for any corrosion
Checks the O2 sensor heater circuit for the proper resistance to specifications
Checks for exhaust leaks before the sensor
Follow the manufacturer's specific pinpoint tests for further diagnosis.
Follow these simple guidelines to prevent misdiagnosis:
Repair any exhaust leaks before the sensor to prevent incorrect readings.
Check the O2 sensor for oil or coolant contaminants from engine leaks.
Repair any harness that is damaged properly without taking shortcuts to prevent repeat failures.
Check the removed O2 sensor for damage from a defective catalyst and replace the catalyst if it is faulty.
The voltage output from the O2 sensor may point to engine and exhaust problems causing the O2 sensors to give erratic output voltages.
The O2 sensor may not read correct if the catalyst is damaged in front of the sensor.
The ECM may stay in open loop until the O2 system is repaired or the O2 sensor starts working again causing extended rich conditions that could possibly damage other engine components.
Repairing or replacing the wiring or connection to the O2 sensor for bank 1 sensor 2
Repairing exhaust leaks or a damaged catalyst
The O2 sensor circuit for bank 1 sensor 2 is used to give a voltage feedback to the ECM to control the fuel and provide information about catalyst operation.
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