P0535 low

Evaporator Temperature Sensor Circuit

The P0535 code means the vehicle's onboard diagnostic system has detected: Evaporator Temperature Sensor Circuit. This is a low severity code.

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Keep driving?: Yes, but fix soon
DIY difficulty: hard
Estimated cost: $100 - $500 (parts and labor)

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Common Symptoms

Check Engine Light on
AC system not regulating temperature properly
Evaporator may freeze up
Inconsistent cabin temperature

Probable Causes (Ranked by Likelihood)

Faulty evaporator temperature sensor Very High
Wiring fault in evaporator sensor circuit High
Corroded connector at evaporator sensor Moderate
HVAC control module failure Low

Step-by-Step Diagnostic Procedure

Read evaporator temperature sensor value with a scan tool and compare to actual temperature
Check evaporator temperature sensor connector and wiring for damage behind the dashboard
Measure sensor resistance and compare to temperature-resistance chart in service manual
Verify HVAC control module is receiving the sensor signal correctly

Frequently Asked Questions

What is the evaporator temperature sensor?

The evaporator temperature sensor monitors the temperature of the AC evaporator core inside the dashboard. It prevents the evaporator from freezing by cycling the compressor off when the evaporator approaches 32 degrees F.

Can a bad evaporator sensor cause the AC to freeze up?

Yes. If the sensor reads warmer than actual temperature, the compressor will not cycle off when needed, allowing the evaporator to freeze. A frozen evaporator blocks airflow and can cause water to drip inside the cabin.

Is the evaporator temperature sensor hard to replace?

The sensor itself is inexpensive, but access can be difficult since it is located inside the HVAC housing behind the dashboard. Some vehicles allow access through a small opening, while others require significant dashboard disassembly.