O2 Sensor Heater Circuit (Bank 2 Sensor 1)
What it means
The engine computer has found that the heater circuit of the bank 2 upstream oxygen sensor is not working properly, a code seen on engines with two banks. The sensor then takes longer to reach working temperature after a cold start, delaying precise fuel control on that bank.
Symptoms4
- Check engine light on.
- Slightly higher fuel use on short trips.
- Higher emissions after a cold start.
- A no-activity code such as P0154 may appear with it.
Possible causes5
- Burned-out heater element inside the sensor.
- Melted wiring or damaged connector near the exhaust manifold behind the engine.
- Blown heater fuse.
- Corroded connector terminals.
- Fault in the control circuit inside the engine computer (rare).
How to diagnose5
- Identify bank 2 and the correct sensor per the manufacturer before removing anything.
- Check the heater fuse, and note whether other heaters are also faulty.
- Unplug the sensor and measure heater resistance, comparing it with the specification and with the matching bank 1 sensor.
- Confirm supply voltage and check the control wire to the computer.
- Inspect the wiring route behind the engine for melting or chafing.
How to fix4
- Repair melted wiring and secure it away from the exhaust.
- Replace a blown fuse after finding the cause.
- Replace the bank 2 upstream oxygen sensor if the heater is open.
- Clear the codes and start the engine from cold to confirm the code does not return.
Repair cost
In Saudi riyals; the highlighted part is the expected range for this fault.
A wiring or fuse repair keeps the cost low; a new sensor raises it, and labor may increase because the bank 2 sensor is hard to reach on some engines.
Prices are rough estimates for common cars at independent workshops and vary with the car and the source of the part.
Prices last updated: September 2026
Frequently asked questions
Should I replace the sensor straight away?
Measure the heater resistance and check the fuse and wiring first; if the heater is fine, a new sensor will not fix the problem.
Why is this sensor hard to reach?
On some cars bank 2 sits close to the firewall or at the back of the engine, so removal needs special tools or lifting the car.
Was this explanation helpful?
Tap the stars to rate; you can change it later.
What was wrong? (optional)
This guide is for information only and does not replace an inspection by a qualified technician. If the fault involves brakes, steering, engine temperature, electrics or refrigerant, do not attempt the repair yourself.
Report a mistake
Spotted something inaccurate? Tell us and we will review and correct it.
Report received — thank you
This is your private tracking link. It shows the status and our reply as soon as it is posted.
The link is saved in this browser only.