P0141 Code: O2 Sensor Heater Circuit Malfunction (Bank 1 Sensor 2)

🟢 Low severity · drivable

Safe to drive — this affects only the downstream sensor's warm-up heater.

What P0141 means

The heater inside the bank 1 downstream oxygen sensor isn't working. The heater just warms the sensor up faster after a cold start; without it, the sensor takes longer to read accurately. It's an electrical fault in the sensor or its heater circuit, and it won't affect how the car drives.

How the system works

Bank 1 sensor 2 is the oxygen sensor after the catalytic converter on the side of the engine with cylinder 1. Its job is to check that the converter is working. Like the upstream sensor it has a built-in electric heater so it reaches working temperature quickly.

The engine computer watches the heater's current. P0141 sets when that current is out of range or missing. The engine's fuelling does not rely on this sensor, so the car drives normally, but the computer cannot run its catalytic converter test until the sensor is warm, and the vehicle can fail an emissions inspection.

Symptoms

Check engine light on
Usually no driving symptoms

Common causes

most common: Faulty downstream oxygen sensor (heater failed)
common: Blown fuse or damaged heater-circuit wiring
less common: Corroded sensor connector

How to diagnose P0141

Check the fuse first. Heater circuits usually share a fuse. If P0141 appears alongside P0135 or P0161, start with the fuse and the shared power feed.
Measure heater resistance. Unplug the sensor and measure across the two heater pins, normally the two wires of the same colour. A few ohms up to around 20 is typical. An open circuit means the heater has failed.
Check for power at the connector. With the engine running, the heater feed on the vehicle side should show battery voltage. If it does not, trace the fuse, relay and wiring.
Inspect the harness under the car. The downstream sensor's wiring runs along the underside, where it can be damaged by road debris, exhaust heat or a previous exhaust repair. Look for melted or pinched sections.
Check the control side. If power is present and the heater tests good, check the wire back to the computer for an open or a short.

How to fix it

Fix	DIY?	Typical cost
Check the O2 sensor heater fuse and wiring	Yes	$0–20
Replace the bank 1 downstream oxygen sensor	Yes	$60–200

Common misdiagnoses

Replacing the catalytic converter. P0141 is an electrical fault in the sensor heater and says nothing about converter condition.
Replacing the upstream sensor by mistake. Sensor 2 is the one after the converter.
Not checking wiring after exhaust work. A harness left resting on the pipe after a muffler or converter job is a common cause.

P0141 vs similar codes

P0135: P0135 is the same heater fault on the upstream sensor of bank 1, the one before the catalytic converter.
P0161: P0161 is the same fault on the downstream sensor of bank 2.
P0136: P0136 concerns the downstream sensor's signal circuit, not its heater.

Frequently asked questions

Is P0141 serious?

No. It only affects the downstream sensor's warm-up heater, so drivability is unaffected.

What causes P0141?

A failed heater element in the downstream oxygen sensor, or a blown fuse.

How much does it cost to fix P0141?

Typically $60–$200 for a downstream oxygen sensor.

Will P0141 cause a failed emissions test?

It can. The check engine light alone fails most inspections, and the catalyst monitor may not complete while the heater fault is present.

Can I replace the downstream oxygen sensor myself?

Usually yes. It needs an oxygen sensor socket and penetrating oil, and it comes out more easily with the exhaust slightly warm. Access under the car is the main difficulty.