Air/Fuel Sensor Heater Circuit (Bank 2 Sensor 1)
What it means
This is a code specific to Lexus (and the Toyota group); the same number may mean a different fault on other makes. It appears on V6 and V8 engines and means the engine computer detected an open or short in the heater circuit of the Bank 2 upstream air/fuel (A/F) sensor, on the side without cylinder 1. This sensor can be harder to reach on some models.
Models covered: Lexus V6/V8 models with A/F sensors, mainly around 1998–2004 (e.g. ES300, RX300, LX470).
Symptoms4
- Check engine light on.
- Slightly higher fuel use, more noticeable on large vehicles such as the LX470.
- Usually no clear change in driving smoothness.
- May appear with P1135 when the shared power feed is the cause.
Possible causes5
- Bank 2 sensor heater burnt out with age.
- Blown fuse feeding the heater, or a failed relay where fitted.
- Wiring damaged by exhaust heat or rubbing on engine parts.
- Corroded or loose connector.
- Control circuit fault inside the engine computer (rare).
How to diagnose4
- Identify the Bank 2 side (the side without cylinder 1) and where the sensor sits on it.
- If P1135 is also stored, check the fuse and shared power feed first.
- Measure heater resistance at the sensor connector and compare with the factory specification.
- Inspect the whole wiring route, especially sections near the exhaust.
How to fix4
- Repair the fuse, wiring or connector after removing the cause of the short.
- Replace the Bank 2 sensor if its heater is open, using a part that matches the vehicle.
- Secure the wiring away from the exhaust with the original clips so the damage does not recur.
- Clear the codes and confirm they do not return after a cold start.
Repair cost
In Saudi riyals; the highlighted part is the expected range for this fault.
A fuse or wire is at the low end; the cost rises with a new sensor and with harder access on some V6 and V8 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
Why does the P1155 repair cost vary between Lexus models?
The Bank 2 sensor location differs by engine and layout; on some it is easy to reach and on others extra parts must come off, which raises labor.
Can the sensor be cleaned instead of replaced?
No. An open heater is an internal electrical failure that cleaning cannot fix. If the heater is confirmed open, the only fix is a new sensor.
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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.
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