AutoCodes – Mercury – P0538 Mercury

P0538 Mercury Code - A/C Evaporator Temperature Circuit High Input

Quick Answer

The A/C Evaporator Temperature (ACET) sensor contains a thermistor which receives a reference voltage from the Powertrain Control Module (PCM). Common causes include Faulty A/C Evaporator Temperature (ACET) Sensor, A/C Evaporator Temperature Sensor harness is open or shorted, A/C Evaporator Temperature Sensor circuit poor electrical connection. Severity is Low - monitor the vehicle and repair when practical. The vehicle can usually be driven if no severe symptoms are present, but symptoms should be checked before extended driving.

What it means: P0538 Mercury indicates A/C Evaporator Temperature Circuit High Input.
Common causes: Common causes include Faulty A/C Evaporator Temperature (ACET) Sensor, A/C Evaporator Temperature Sensor harness is open or shorted, A/C Evaporator Temperature Sensor circuit poor electrical connection.
Severity: Low - monitor the vehicle and repair when practical.
Can I drive?: The vehicle can usually be driven if no severe symptoms are present, but symptoms should be checked before extended driving.

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Code Popularity 677

How popular is this code, among other codes? Low

Repair Importance Level

Low (Monitor) (1 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on Jul 28, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P0538 Mercury Description

The A/C Evaporator Temperature (ACET) sensor contains a thermistor which receives a reference voltage from the Powertrain Control Module (PCM). The thermistor then varies the resistance to the reference voltage based on the evaporator discharge air temperature. The resulting voltage is returned to the PCM where it is interpreted as an evaporator discharge air temperature reading.
The PCM maintains evaporator core temperature and prevents icing of the evaporator core, by disengaging the A/C compressor clutch (non-hybrid) or decreasing the electric A/C compressor speed (hybrid) when the evaporator A/C Evaporator Temperature sensor reading falls below acceptable levels, and by engaging the A/C compressor clutch (non-hybrid) or increasing the electric A/C compressor speed (hybrid) when the discharge air temperature rises above acceptable levels.
The A/C Evaporator Temperature sensor is located inside of the heater core and evaporator core housing in the air-stream leaving the evaporator core.
The Diagnostic Trouble Code (DTC) indicates the A/C Evaporator Temperature sensor signal input is greater than Self-Test minimum. Self-Test maximum is 4.5 volts.

OBDII Code P0538 Mercury - A/C Evaporator Temperature Circuit High Input - AutoCodes.com — P0538 Mercury Code - A/C Evaporator Temperature Circuit High Input

What does this mean?

What are the Possible Causes of the DTC P0538 Mercury?

Faulty A/C Evaporator Temperature (ACET) Sensor
A/C Evaporator Temperature Sensor harness is open or shorted
A/C Evaporator Temperature Sensor circuit poor electrical connection
Faulty Powertrain Control Module (PCM)

How to Fix the DTC P0538 Mercury?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0538 Mercury code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

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About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about P0538 Mercury Code

1. What are the common symptoms of OBDII code P0538 in a Mercury related to the A/C Evaporator Temperature Circuit High Input?

The common symptoms include the A/C system not blowing cold air, inconsistent cooling performance, and the A/C compressor not engaging.

2. What are some possible causes of the OBDII code P0538 in a Mercury indicating A/C Evaporator Temperature Circuit High Input?

Possible causes include a faulty evaporator temperature sensor, wiring issues in the temperature circuit, a defective A/C control module, or a problem with the A/C compressor.

3. How can I diagnose the OBDII code P0538 in a Mercury related to the A/C Evaporator Temperature Circuit High Input?

Diagnosis involves using a scan tool to retrieve the trouble code, inspecting the evaporator temperature sensor and its wiring for damages, and testing the A/C system components for proper functionality.

4. Can I continue driving my Mercury with OBDII code P0538 indicating A/C Evaporator Temperature Circuit High Input?

It is not recommended to drive your vehicle with this code as it can lead to further A/C system damage and discomfort due to lack of cooling.

5. How can I repair OBDII code P0538 in a Mercury for the A/C Evaporator Temperature Circuit High Input?

Repairing may involve replacing the evaporator temperature sensor, repairing or replacing damaged wiring, resetting the trouble code with a scan tool, and testing the A/C system for proper operation.

6. Are there any DIY tips for troubleshooting OBDII code P0538 in a Mercury related to the A/C Evaporator Temperature Circuit High Input?

DIY tips include checking the A/C fuses, visually inspecting the sensor and wiring for any visible issues, and ensuring the A/C system is properly charged with refrigerant.

7. Is it necessary to visit a mechanic for OBDII code P0538 in a Mercury indicating A/C Evaporator Temperature Circuit High Input?

It is recommended to visit a qualified mechanic or automotive technician to accurately diagnose and repair the issue to ensure proper functionality of the A/C system.

8. Can weather conditions affect the occurrence of OBDII code P0538 in a Mercury for the A/C Evaporator Temperature Circuit High Input?

Extreme weather conditions or temperature fluctuations can sometimes affect the A/C system performance, potentially triggering this code.

9. How long does it typically take to repair OBDII code P0538 in a Mercury related to the A/C Evaporator Temperature Circuit High Input?

The repair time can vary based on the exact cause of the issue, but it may take a few hours to a full day to diagnose and fix the problem.

10. Is resetting the trouble code enough to fix OBDII code P0538 in a Mercury indicating A/C Evaporator Temperature Circuit High Input?

Resetting the code may temporarily clear the warning light, but it is essential to address the root cause of the problem to prevent it from recurring.