Air-Fuel Ratio Sensor Heater Circuit Response Time -- Bank 1 Sensor 1 (Toyota/Lexus)
What does P1135 mean?
The P1135 code means the vehicle's onboard diagnostic system has detected: Air-Fuel Ratio Sensor Heater Circuit Response Time -- Bank 1 Sensor 1 (Toyota/Lexus). This is a moderate severity code.
Common Symptoms
- Check Engine Light on
- Poor fuel economy
- Rough idle when engine is cold
- Higher emissions during warmup period
- May fail emissions test
Probable Causes (Ranked by Likelihood)
- Failed air-fuel ratio sensor heater element Very High
- Damaged wiring to air-fuel ratio sensor High
- Blown air-fuel ratio sensor heater fuse Moderate
- Corroded connector at air-fuel ratio sensor Moderate
- PCM heater control circuit fault Low
Step-by-Step Diagnostic Procedure
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Check the air-fuel ratio sensor heater fuse
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Measure heater circuit resistance -- compare to specification (typically 4-40 ohms)
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Check the wiring and connector at the air-fuel ratio sensor on bank 1
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Monitor sensor warmup time with a scan tool -- should reach operating temperature within 30-60 seconds
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Verify voltage supply to the heater circuit
Frequently Asked Questions
Can I drive with code P1135?
You can drive short distances. The engine will run slightly rich during cold starts until the sensor heats up on its own from exhaust heat. Fuel economy will be worse than normal.
What causes P1135 on Toyota/Lexus?
The internal heater element in the air-fuel ratio sensor has failed or is responding too slowly. These sensors use a heater to reach operating temperature quickly, and the heater wears out over time.
Is P1135 expensive to fix?
No. The air-fuel ratio sensor typically costs $80 to $200 for a quality aftermarket or OEM part. It is a fairly easy DIY replacement on most Toyota and Lexus vehicles.