P1135

Air/Fuel Sensor Heater Circuit (Bank 1 Sensor 1)

Car Fault Codes Toyota Emissions & exhaust

Can you still drive? Yes, normally

Who can fix it? DIY with some experience

Typical repair time 30 minutes – 1.5 hours

Typical cost SAR 100 to 900

What it means

This is a Toyota-specific code; the same number may mean something different on other makes. The air/fuel (A/F) sensor needs a built-in heater to reach working temperature quickly, and the engine computer detected abnormal heater current from an open or short. Most often the heater inside the sensor has burnt out or the fuse feeding it has blown.

Models covered: Toyota models with air/fuel ratio (A/F) sensors, mainly model years around 1998–2004 (e.g. Camry, Corolla, RAV4, Highlander, Sienna, Tacoma, Tundra); later models use generic codes (P2195–P2198, P0031/P0032).

Symptoms4

Check engine light on.
Slightly higher fuel use, especially on short trips.
Delayed precise mixture control after a cold start.
Usually no obvious driveability symptoms.

Possible causes5

Open heater element inside the sensor (most common).
Blown fuse feeding the heater, or a failed relay on models that use one.
Wiring melted or rubbing on the exhaust.
Corroded or loose sensor connector.
Fault in the heater control circuit inside the engine computer (rare).

How to diagnose4

Check the fuse feeding the sensor heater; if it is blown, find the short before replacing it.
Unplug the sensor and measure heater resistance across its terminals against the Toyota specification.
Confirm battery voltage reaches the heater supply terminal with the ignition on.
Inspect wiring near the exhaust for melting or chafing.

How to fix4

Replace a blown fuse or failed relay after fixing the cause of the short.
Repair damaged wiring or the connector.
Replace the A/F sensor if its heater is open, since the heater is not sold separately.
Clear the codes and confirm the code stays away after a cold start.

Repair cost

0–500

500–2,000

2,000–5,000

5,000+

In Saudi riyals; the highlighted part is the expected range for this fault.

A fuse or wire repair is cheap; an open heater means replacing the whole sensor, which is the top of the range.

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

Can I drive with P1135?

Usually yes; it does not harm the engine directly. Mixture control is delayed after every cold start, so fuel use rises a little and it is best fixed soon.

What is the generic equivalent?

Later Toyota models log the same fault as generic P0031 (circuit low) or P0032 (circuit high) for the Bank 1 upstream sensor heater.

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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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