Error P0136 – how to fix?

Code definition P0136

O2 Sensor Circuit Malfunction (Bank 1, Sensor 2)

What does the code P0136 mean?

P0136 is a general OBD-II code indicating that the bank 1 O2 sensor is not within the minimum and maximum voltage calibrated limits for the ECM.

What causes the code P0136?

• The ECM monitors the O2 sensor high and low voltages. This code appears when the voltage limits do not fall within the 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 to control fuel injection with known values.
• There is a leak in the exhaust system or a damaged catalyst in front of the sensor.

What are the symptoms of the P0136 code?

• The engine can run with an excessively rich composition if it goes into open circuit.
• If the spark plugs become dirty over time, the engine may stop working.
• The Check Engine light will come on.
• You may have exhaust gas leaks or loss of power due to a clogged or damaged catalytic converter.

How does the mechanic diagnose the P0136 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.
• Check the O2 sensor heating circuit for proper resistance as per specification.
• 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 P0136 code

Follow these simple tips to avoid misdiagnosis:

• Repair any leak in the exhaust system upstream of the sensor to avoid incorrect readings.
• Check the O2 sensor for contamination by oil or coolant from engine leaks.
• Repair damaged harnesses properly, taking no shortcuts to avoid repeated failures.
• Check that the removed O2 sensor is not damaged by a faulty catalytic converter and replace the catalytic converter if it is faulty.

How serious is the P0136 code?

• The O2 sensor output voltage can indicate problems with the engine and exhaust system that are causing the O2 sensors to provide erratic output voltages.
• The O2 sensor may not read properly if the catalytic converter is damaged in front of the sensor.
• The ECM can remain in open loop until the O2 system is repaired or the O2 sensor starts working again, causing abundant long-term conditions that could possibly damage other engine components.

What repairs can fix the code P0136?

1. Replace O2 sensor in bank 1 sensor 2.
2. Repair or replace wiring or connection to O2 sensor for bank 1 of sensor 2
3. Repair the exhaust leaks or the damaged catalytic converter

Additional notes regarding code P0136

The bank 1 sensor 2 O2 sensor circuit is used to provide voltage feedback to the ECM for fuel control and catalyst performance information.