Evaporator Temperature Sensor Circuit Low
The P0537 code means the vehicle's onboard diagnostic system has detected: Evaporator Temperature Sensor Circuit Low. This is a low severity code.
- 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 compressor may not engage
- No cold air from AC
- HVAC system in protection mode
Probable Causes (Ranked by Likelihood)
- Short to ground in evaporator temperature sensor wiring Very High
- Failed sensor with internal short (low resistance) High
- Water intrusion in sensor connector Moderate
- Pinched sensor wire behind dashboard Moderate
Step-by-Step Diagnostic Procedure
-
Read evaporator temperature sensor value; an extremely cold reading when AC is off confirms circuit low
-
Disconnect sensor and check for short to ground on the signal wire
-
Measure sensor resistance; very low resistance confirms internal short
-
Inspect wiring behind dashboard for pinched or damaged wires
Frequently Asked Questions
Why does the AC compressor not engage with P0537?
When the sensor reads extremely low (falsely indicating a very cold evaporator), the HVAC system disables the compressor to prevent further cooling. The system thinks the evaporator is already frozen.
What does circuit low mean for P0537?
Circuit low means the sensor signal voltage is below the expected minimum, making the system read an extremely cold temperature. This is typically caused by a short to ground in the wiring or a sensor with reduced internal resistance.
Can water damage cause P0537?
Yes. The evaporator area produces condensation during AC operation. If drain lines become clogged, water can accumulate and reach the sensor connector, causing corrosion and short circuits.
Sources
This page is built from documented references. Verify against your own service info before repair work.
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