P0147 code definition
O2 Sensor Heater Circuit Malfunction (Bank 1 Sensor 3)
What the P0147 code means
P0147 is the OBD-II generic code indicating the Engine Control Module (ECM) has tested the O2 sensor heater circuit during startup and detects problems with the bank 1 sensor 3 O2 sensor heater circuit.
What causes the P0147 code?
The ECM tests the O2 sensor heater circuits at startup for excessive current draw, opens, or shorts. In the case of the P0147 code, the ECM detects a short, open, or excessive current draw in the O2 bank 1 sensor 3 heater circuit.
What are the symptoms of the P0147 code?
The engine will not run any different, since the O2 sensor is only used for catalyst efficiency and not for fuel control.
The Check Engine Light will be illuminated by the ECM after the O2 sensor fails the test.
How does a mechanic diagnose the P0147 code?
- Scans the ECM for codes and freeze frame data and documents the information
- Reruns the O2 sensor tests to see if the sensor fails again; if it fails, performs the pinpoint test for the sensor
- Tests the O2 sensor heater circuit for power and ground at the connector end
- Measures resistance of the O2 sensor heater circuit and replaces the sensor if it fails
- Repairs the O2 sensor wiring if the wiring is tested to be faulty
- Clears and retests system for any more faults
Common mistakes when diagnosing the P0147 code?
Follow these simple guidelines to prevent misdiagnosis:
Check the O2 sensor wire harness cover for contaminants entering into the covering that can short the sensor heater circuit.
Check the O2 sensor for oil or coolant contaminants that can short the sensor.
How serious is the P0147 code?
The code will not affect the way the engine will run if the sensor is the fault of the code. The O2 sensor 3 for bank 1 is only used to check catalyst efficiency.
The code will cause a failure for emission testing due to the Check Engine Light being on, and catalyst monitors not passing.
What repairs can fix the P0147 code?
Replacing the O2 sensor for bank 1 sensor 3
Repairing or replacing the wiring or connection to the O2 sensor for bank 1 sensor 3
Replacing the fuse to the heater circuit for the O2 sensor heater circuit
Additional comments for consideration regarding the P0147 code
The O2 sensor heater circuit for bank 1 sensor 3 is used to heat the internal sensor of the O2 sensor so the sensor can start working faster and be more sensitive than sensors without the heater.
Need help with a P0147 code?
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This article originally appeared on YourMechanic.com as P0147 OBD-II Trouble Code: O2 Sensor Heater Circuit Malfunction (Bank 1, Sensor 3) and was authored by Jay Safford.