Car & driving · Free
P0141: O2 sensor heater circuit (bank 1, sensor 2)
P0141 means the heater of the rear oxygen sensor, the one after the catalytic converter on bank 1, is not working. The engine runs as before, but the car can no longer check its catalytic converter properly until this is fixed.
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- Runs on your device
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Check your car for P0141
Runs on your device
Connect your OBD2 adapter
- Plug the adapter into the OBD2 port – usually under the steering wheel, near the pedals.
- Switch the ignition on, or start the engine.
- Bluetooth adapter? Turn Bluetooth on. Nothing else to set up.
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What P0141 means
The rear O2 sensor does not control the mixture. Its job is to judge the catalytic converter: a healthy converter leaves the rear sensor reading almost steady, a worn one makes it swing. The exhaust behind the converter is cooler, so the rear sensor depends on its heater to reach working temperature at all, especially on short trips and at idle.
The engine computer checks the heater current and stores P0141 when it is missing or out of range. Until the heater works, the computer cannot trust the rear sensor, so it skips or fails its catalyst test. That is why P0141 often comes with an incomplete catalyst monitor, and sometimes with a false P0420.
Symptoms of P0141
- Nothing you notice while driving: the rear sensor does not control the engine.
- The catalytic converter self-test in Inspection never completes.
- An emissions inspection that fails because of the code or the missing self-tests.
- Sometimes P0420 a few days later.
Causes of P0141, cheapest first
Work down the list in order: the first checks cost little or nothing, the last ones are jobs for a workshop.
Corrosion in the plug under the car
The plug often sits on the underbody or next to the gearbox tunnel, where water and road salt get in. Unplug it, look for green deposits, then clean and dry the contacts. This alone fixes many P0141 codes.
Wiring hit by heat, stones or speed bumps
A harness that has slipped out of its clips can touch the exhaust, get hit by stones or scrape on the road. Follow it from the sensor to the plug.
Damage from recent exhaust work
A new catalytic converter or exhaust section is a common moment for a stretched wire or a plug left hanging. If the code appeared right after exhaust repairs, check that work first.
A burnt-out heater element
On older sensors the heater simply fails. Measure its resistance on the sensor side of the plug; an open circuit means a new sensor. Rear sensors usually cost less than front ones.
A blown fuse or the control unit
Check the heater fuse, especially when other heater codes are stored too. A fault in the engine computer is rare and comes last.
Can you drive with P0141?
Safe to drive. P0141 does not change how the engine runs or how much fuel it uses in a way you would notice. It stops the car from checking its catalytic converter, though, so fix it within the next few weeks and before an emissions inspection.
Check P0141 with OBD Studio
Connect your adapter above, or try the demo car, then:
- In Live data, graph O2 sensor 2 voltage during the first minutes after a cold start. With a working heater the rear sensor wakes up within a minute or two; with a dead heater it stays flat near its resting value much longer.
- Once the engine is warm, a rear sensor behind a healthy converter settles at a fairly steady value, often around 0.6 to 0.7 V. A sensor that still does not react after a long drive points to the sensor itself, not only its heater.
- In Inspection, check the Catalytic converter and O2 sensor heaters monitors; on cars with CAN, Read self-tests shows the heater result for bank 1, sensor 2.
- After the repair, clear the code. The catalyst test needs several mixed drives before it shows Complete again.
More fault code guides
Each of these codes has its own page with causes ranked by cost and the checks that go with them.
- P0420Catalyst efficiency below threshold
- P0171System too lean
- P0300Random or multiple misfire
- P0455EVAP system large leak
- P0442EVAP system small leak
- P0128Engine warms up too slowly
- P0172System too rich
- P0401EGR flow too low
- P0101Air flow sensor implausible
- P0135Front O2 sensor heater
- P0016Crankshaft and camshaft out of step
- P0011Intake camshaft timing over-advanced
- P0113Intake air temperature sensor high
- P0457Fuel cap loose or missing
- P0299Turbo underboost
- P0700Transmission control system fault
- P0087Fuel rail pressure too low
- P0562System voltage low
- U0100Lost communication with engine computer
More OBD Studio pages
Frequently asked questions
Where is bank 1 sensor 2?
After the catalytic converter, in the exhaust pipe on the side of the engine with cylinder 1. On most four-cylinder cars it is the only sensor behind the converter, usually reached from under the car.
Does P0141 mean my catalytic converter is bad?
No. P0141 concerns the sensor heater only. But until the rear sensor works properly, the car cannot test the converter, and a false P0420 is possible.
Do I need an original sensor for the rear position?
A sensor made for your car with the right plug is the safest choice. Universal sensors that need their wires spliced can work, but a poor joint under the car is exactly where new corrosion starts.
Can I read P0141 without going to a workshop?
Yes. With any ELM327-compatible Bluetooth LE or USB adapter, OBD Studio on this page reads P0141 and every other stored code for free, shows the freeze frame and clears the code after the repair. Nothing to install, no account.
