Oxygen (lambda) sensors

P1155 Air/fuel ratio sensor heater: circuit fault (bank 2, sensor 1)

By: Diagno editorial team · Updated: 2026-10-15

P1155 means: Air/fuel ratio sensor heater: circuit fault (bank 2, sensor 1). The oxygen sensor has a heater so it warms up quickly. OK to drive, but have it checked soon. The repair usually costs about €60–250 in Estonia. The most common cause: sensor heater element burnt out.

Is it safe to drive?OK to driveOK to drive, but have it checked soon.

Typical repair cost€60–250parts and labour in Estonia

What it means

The oxygen sensor has a heater so it warms up quickly. If the heater doesn't work, the sensor gives no proper reading on a cold engine and fuel use goes up.

This is a make-specific code (Toyota). The exact meaning can vary by model and year.

What you may notice

Engine light on
Slightly higher fuel consumption
Usually no change in how the car drives

What could be wrong

1Sensor heater element burnt out
2Oxygen sensor heater fuse blown
3Wire or connector melted or broken
4Engine computer fault (rare)

Repair difficulty: Easy

What you can check yourself

Check the oxygen sensor heater fuse. Make sure the sensor wire isn't touching the hot exhaust. You can do the simpler checks yourself.

How we fix it

We measure heater resistance and supply
We replace the fuse or repair the wire
We replace the oxygen sensor

Standard SAE description: A/F Sensor Heater Circuit (Bank 2 Sensor 1)

This code usually comes with: Check engine lightSee what the light means →

Want a definite answer?

Bring the car to our workshop in Estonia for diagnostics. We read the fault codes, test the sensors and tell you what is wrong. Repair price depends on the work involved, generally €45 per hour.

Book a diagnostic check

Questions

What does fault code P1155 mean?

Air/fuel ratio sensor heater: circuit fault (bank 2, sensor 1). The oxygen sensor has a heater so it warms up quickly. If the heater doesn't work, the sensor gives no proper reading on a cold engine and fuel use goes up.

Can I drive with code P1155?

OK to drive, but have it checked soon.

How much does it cost to fix P1155?

Roughly €60–250 in Estonia. The price depends on exactly what has failed and on the car.

How is P1155 fixed?

We measure heater resistance and supply. We replace the fuse or repair the wire. We replace the oxygen sensor.

Based on AI combined with our hands-on workshop experience and knowledge. This information is general and prices are approximate (Estonian workshop rates). The same code can mean different things on different cars. Only an inspection of the car gives a definite answer.