P0538

A/C Evaporator Temperature Sensor Circuit High

Q: Is it safe to drive with P0538?

Yes. It only affects the A/C system; the engine runs normally. Fix it if you want reliable cooling and to clear the light.

Q: Can I just clear P0538?

It returns until the sensor or its wiring is repaired. Clearing only resets the light.

A/C & climate control Generic OBD-II Low

What it means

P0538 means the ECM or HVAC module sees an abnormally high voltage on the A/C evaporator temperature sensor circuit — usually an open circuit, a short to power, or a failing sensor. This sensor helps prevent the evaporator from freezing and controls compressor cycling, so a bad reading can weaken or disable cooling. It only affects the A/C, not how the engine runs.

Low

Can I keep driving? Safe to drive — only the air-conditioning is affected. The engine runs normally; you may just get weaker or inconsistent A/C cooling.

Real-world scan data

Seen in

118

scans in the past year

Found in

<0.1%

of scans

<0.1%

of scans that found faults

Figures reflect only diagnostic scans recorded through our own apps and tools. Cars are typically scanned because a symptom or warning light prompted it, so these counts describe our scan records — not the incidence of faults in any model, and not the quality, reliability, or safety of any vehicle. No comparison between manufacturers or models is implied. All trademarks belong to their respective owners; no affiliation or endorsement is implied.

Common symptoms

What you'll notice

Weak, inconsistent, or non-functioning A/C cooling
A/C compressor may cycle oddly or stay off
Check-engine or A/C warning light on
Engine performance unaffected

Common causes

Most likely first

Faulty A/C evaporator temperature sensorLikely
Open circuit or short-to-power in the sensor wiring (high voltage)Common
Corroded or loose connector at the sensorCommon
Damaged wiring in the HVAC harnessLess often
HVAC control module or ECM fault (rare)Less often

How to diagnose & fix

Work through it in order

Read freeze-frame data and confirm the code with a scan tool.
Locate the evaporator temperature sensor and inspect its connector and wiring.
Check for an open circuit or short to power causing the high reading.
Compare the sensor resistance/voltage against spec at a known temperature.
Replace the sensor if it reads out of range. Clear and re-test.

FAQ

Quick answers

Is it safe to drive with P0538?+

Yes. It only affects the A/C system; the engine runs normally. Fix it if you want reliable cooling and to clear the light.

Can I just clear P0538?+

It returns until the sensor or its wiring is repaired. Clearing only resets the light.

Read & clear P0538 yourself

Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.

▶ Get it on Google Play

✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX