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P0135 is a diagnostic trouble code (DTC) for "O2 Sensor Heater Circuit Malfunction (Bank 1, Sensor 1)". 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 is on diagnostic inspection. 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 Heater Circuit Malfunction (Bank 1, Sensor 1)
P0135 is the OBD-II generic code indicating the engine control module (ECM) has tested the O2 sensor heater circuit and has detected a problem with the bank 1 sensor 1 O2 sensor heater circuit.
The ECM tests the O2 sensor heater circuit at first startup for excessive current draw and opens or shorts.
The ECM detects a short or open circuit, or an excessive current draw in the heater circuit.
The ECM will not have any O2 sensor feedback until the O2 sensor gives an input.
The engine may run rough until the exhaust gets hot enough to activate the O2 sensor to start giving an output voltage.
The Check Engine Light will be illuminated indicating a problem.
Visually checks the electrical connections and wire harness to the bank 1 sensor 1 O2 sensor
Scans codes and documents freeze frame data then clear codes to verify failure
Monitors O2 sensor data to see if the heater circuit is working
Tests the O2 sensor connector for the proper input voltage from the ECM for the heater circuit
Checks the O2 sensor heater circuit for the proper resistance to specifications
Follows the manufacturer's specific pinpoint tests for further diagnosis
O2 sensors are the fuel control feedback the ECM needs to properly control the injectors.
The ECM stays in open loop until the O2 system is repaired or the O2 sensor starts working again.
The engine stuck in open loop will run extra rich and will burn more fuel and start to build carbon.
The O2 sensor heater circuit is used to heat the internal parts of the O2 sensor to help it start give feedback to the ECM quicker. If the heater fails, the O2 sensor may still give feedback to the ECM but will take more than the normal time of less than two minutes.
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