Oxygen sensor heater circuit fault (Bank 2 Sensor 1)
The controller detected a fault in the heater circuit for the specified oxygen sensor. The heater brings the sensing element to operating temperature and is separate from its oxygen signal circuit. A supply fault, wiring damage or failed heater is possible; this code does not establish catalytic converter failure. Bank 2 is opposite the bank containing cylinder 1; sensor 1 is before the catalytic converter.
Can I keep driving?
If the light is steady and the vehicle behaves normally, contact a shop for vehicle-specific urgency advice. If there is severe shaking, stalling, major power loss, a flashing light, smoke or a fuel smell, pull over safely and arrange assistance.
What does this code mean for your car?
The same code can need different checks depending on the model and engine. Enter your vehicle details to find relevant sources and checks.
Symptoms
- Check engine light, possibly without noticeable driving symptoms
- Delayed sensor operation after a cold start
- Rough idle or changed fuel economy if mixture control is affected
Possible causes
- 1Open circuit, short or heat-damaged connector in the heater circuit
- 2Fuse, power supply or heater control problem according to the vehicle diagram
- 3Failed heater element inside the specified sensor
These possibilities are not ranked by frequency and do not diagnose your vehicle.
Checks you can safely do yourself
Safe checks only: engine off and cold, car on level ground.
- Save all codes and any freeze-frame data your scanner displays before clearing or repairs.
- Note accompanying fuel-trim, misfire or sensor-heater codes. Do not touch sensors or wiring on a hot exhaust system or crawl under the vehicle.
When you need a shop
Identify Bank 2 Sensor 1 from the vehicle exhaust diagram. Have the shop test heater supply, fuse and control, and test the heater circuit isolated as specified by the manufacturer. Replace a sensor only after separating heater-element failure from wiring or control faults.
How much does it cost?
A US repair estimate needs a diagnosis and a local shop quote.
We do not have a verified US repair quote for this fault. Request 2-3 itemized estimates after diagnosis; vehicle, parts and labor determine the cost.
Get 2-3 quotes
Investigate this code for my carFAQ
Can I keep driving with P0155?
If the light is steady and the vehicle behaves normally, contact a shop for vehicle-specific urgency advice. If there is severe shaking, stalling, major power loss, a flashing light, smoke or a fuel smell, pull over safely and arrange assistance.
What can cause this code?
Possibilities include open circuit, short or heat-damaged connector in the heater circuit; fuse, power supply or heater control problem according to the vehicle diagram; failed heater element inside the specified sensor. The code does not rank causes or identify a part that must be replaced.
Does clearing the code fix the fault?
No. Clearing the code does not repair its cause or prove the fault is absent. It can erase diagnostic data and reset readiness monitors. Even if the code does not reappear immediately, the repair needs verification using the tests appropriate to the vehicle.
What if this code appears during a pre-purchase check?
Arrange an independent professional inspection before buying, including stored data, readiness status and written diagnostic findings. Identify Bank 2 Sensor 1 from the vehicle exhaust diagram. Have the shop test heater supply, fuse and control, and test the heater circuit isolated as specified by the manufacturer. Replace a sensor only after separating heater-element failure from wiring or control faults.
How much does repairing P0155 cost?
We do not have a verified US repair quote for this fault. Request 2-3 itemized estimates after diagnosis; vehicle, parts and labor determine the cost.