P0147: O2 Sensor Heater Circuit, Bank 1 Sensor 3
P0147 means the engine computer found a problem in the heater circuit of the third oxygen sensor on bank 1, a sensor that only some vehicles have. It is not urgent, because the car usually drives normally, but it turns on the check engine light and affects emissions monitoring.
You can keep driving
The data lists no limp mode and usually no noticeable change in driving, so short-term driving is generally fine. The fault still leaves the converter unmonitored and the check engine light on, so plan the repair rather than ignoring it.
What it means
An oxygen sensor measures how much oxygen is left in the exhaust, and it has to be hot to work. A small built-in heater gets it up to temperature quickly. Bank 1 is the side of the engine that holds cylinder 1. Sensor 3 is a third sensor placed behind a second converter or converter brick, and it is only fitted on some vehicles, such as the Jaguar Land Rover 3.0 V6 supercharged (2013-2016) and certain Ford systems. On Ford vehicles, the computer checks the heater's driver voltage continuously and checks the heater current once per drive cycle, after the sensor is above about 120 °C and has been heating for 30 seconds. A current below about 0.22 to 0.465 A (depending on the sensor supplier) or above 3 A counts as a fault. When P0147 sets, the computer stops using this sensor for downstream fuel trim (small fuel corrections) and can no longer evaluate the converter. There is no limp mode.
Likely causes
- Burnt-out heater element in the sensorVery likely
The heater is inside the sensor, and when it fails the sensor has to be replaced.
- Open heater supply (fuse or relay) or control wirePossible
If power or the control signal does not reach the heater, the circuit reads as open and the current stays too low.
- Corroded connector with high contact resistanceLess likely
Corrosion in the plug restricts current to the heater and can trigger the fault.
What you may notice
- Check engine light on, usually after two drive cycles
- Follow-up codes for sensor 3 are possible
- Usually no noticeable change in driving
What to check, cheapest first
- 1Read the codes and note any related ones, such as P0055 (heater resistance) or P0141, which point to other heater circuits. · you can do it
- 2Check the fuse and relay that supply the oxygen sensor heaters, using the owner's manual or fuse box diagram. · you can do it
- 3Inspect the sensor 3 connector and wiring for corrosion, damage, or loose pins. · you can do it
- 4Confirm your vehicle actually has a sensor 3 and locate it behind the second converter on bank 1. · you can do it
- 5Measure heater supply voltage, control signal, and heater current at the sensor connector to separate a wiring fault from a failed heater. · mechanic
- 6Replace the sensor if the heater is dead, clear the code, and complete a drive cycle to confirm the fix. · mechanic
Related codes
Frequently asked questions
Can I drive with a P0147 code?+
Generally yes. The data lists no limp mode and usually no change in driving. The converter goes unmonitored, so repair it soon.
Can a loose gas cap cause P0147?+
No. P0147 is an electrical fault in the sensor's heater circuit. A gas cap problem sets different codes.
Will P0147 pass an emissions test?+
Probably not. The code is emissions-relevant and keeps the check engine light on, which usually causes a failed inspection until it is repaired.
How hard is the repair?+
It is rated easy and can be done at home. The estimate is about 0.2 to 1 hour, most often by replacing the sensor.
Written with the help of AI from the public OBDex definition (CC0). Each make may use the code differently. Updated: 2026-11-10