P0537Generic code

P0537 Code: A/C Evaporator Temperature Sensor Circuit Low

The P0537 code means the A/C evaporator temperature sensor signal is below its minimum value. The air conditioner may lose its freeze protection. It usually comes from the signal wire shorted to ground or from a missing reference voltage.

Severity
Low
Can I keep driving?
Yes, no immediate risk
Estimated cost
$30 to $350
Difficulty
Medium
System
Computer and Outputs
Applies to
All OBD2 vehicles

Updated Reviewed by Renzo Chacca

On this page

What the P0537 code means

The sensor measures the temperature of the air conditioning evaporator to keep it from freezing: when it gets close to 0 °C (32 °F), the compressor disengages for a moment.

The sensor changes its resistance with temperature, and the computer reads the resulting voltage. A low signal, which is what the P0537 code reports, is usually caused by the signal wire shorting to ground or by a missing reference.

If the signal fails, the compressor may stay disabled (no cooling) or run without control and freeze the evaporator (the air stops coming out with force). The sensor is usually inside the air conditioning housing, behind the dash.

To confirm it, unplug the component with the key on and watch what happens to the reading or the code. If the value jumps to the opposite extreme, the wiring is fine and the component is the one pulling the signal to ground. If nothing changes, look for the short in the wire, starting where the harness rubs against the engine, the chassis or the exhaust.

P0537 code symptoms

  • Check engine light on.
  • Air conditioner with no freeze protection.
  • The air conditioner cools poorly or on and off.
  • Airflow drops after a while (frozen evaporator).

Likely causes of the P0537 code

  1. Signal wire shorted to ground. The harness rubs against the engine, the chassis or a bracket.
  2. Reference supply shorted. If several sensors fail at once, suspect the shared reference.
  3. Damaged sensor with an internal short.
  4. Connector with water or corrosion. It creates a path to ground.

How to diagnose the P0537 code step by step

  1. Read the sensor value on the scan tool and compare it with what you expect.
  2. Inspect the connector for corrosion, water or loose pins.
  3. Check the supply and ground with the key on: the reference should be correct, with less than 0.1 V of voltage drop on the ground.
  4. Measure the signal with the connector plugged in and watch whether it changes with the condition.
  5. Do a wiggle test on the harness with the scan tool in graph mode.
  6. Check the continuity of each wire to the computer (under 1 ohm).

How to fix the P0537 code

  • Repair the connector or the wiring.
  • Replace the sensor if the tests confirm it is bad.
  • Correct the real condition if there is one.
  • Clear the codes and verify with a road test.

Technical reference data

  • Two-wire NTC thermistor.
  • The compressor disengages when the evaporator reaches 0 to 3 °C (32 to 37 °F).
  • These values are a general guide: check the manufacturer data for your vehicle.

Brand-specific notes

On many vehicles, getting to the sensor means taking part of the dashboard apart, so the labor is often worth more than the part.

Frequently asked questions about P0537

What does the P0537 code mean?
It is a generic OBD2 code that means the A/C evaporator temperature sensor signal is below its minimum value. In practice that points to a signal wire shorted to ground or a missing reference.
Can I drive with a P0537 code?
Yes, with some caution. The engine runs normally, but the air conditioner may not cool or may ice up and lose airflow until the fault is repaired.
Do I have to replace the sensor?
Only if the tests confirm it. The connector and the wiring fail just as often.
What does the evaporator temperature sensor do?
The sensor measures the temperature of the air conditioning evaporator to keep it from freezing: when it gets close to 0 °C (32 °F), the compressor disengages for a moment.
How much does it cost to fix P0537?
As a rough guide, between $30 and $350. A wiring or connector repair is at the low end, and a new sensor with the dash work is at the high end.
Will a P0537 code clear itself?
Only if the short was temporary, for example water in the connector that dried out. A wire rubbing on metal will bring the P0537 code back.
What is the most common cause of P0537?
A signal wire shorted to ground, usually where the harness rubs against the engine, the chassis or a bracket. A short in the shared reference supply and a damaged sensor follow.

Related codes

Questions about the P0537 code

There are no questions about this code yet. Tell us about your case: vehicle, symptoms and what you have already checked.