AutoCodes – Ford – P0538 Ford

P0538 Ford 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 Ford 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 11,734

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
Tech Notes ▶
Cost to Diagnose
Comments
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Code P0538 Ford 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 Ford - A/C Evaporator Temperature Circuit High Input - AutoCodes.com — P0538 Ford Code - A/C Evaporator Temperature Circuit High Input

What does this mean?

What are the Possible Causes of the DTC P0538 Ford?

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 Ford?

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 does this mean?

Code Tech Notes

User Submitted Video

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0538 Ford 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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Information for Specific Ford Models

P0538 1997 Ford F150 — A/C Evaporator Temperature Circuit High Input
P0538 1998 Ford F150 — A/C Evaporator Temperature Circuit High Input
P0538 1999 Ford F150 — A/C Evaporator Temperature Circuit High Input
P0538 2000 Ford F150 — A/C Evaporator Temperature Circuit High Input
P0538 2001 Ford F150 — A/C Evaporator Temperature Circuit High Input
P0538 2002 Ford F150 — A/C Evaporator Temperature Circuit High Input
P0538 2003 Ford F150 — A/C Evaporator Temperature Circuit High Input
P0538 2006 Ford Fusion — A/C Evaporator Temperature Circuit High Input
P0538 2007 Ford Fusion — A/C Evaporator Temperature Circuit High Input
P0538 2008 Ford Fusion — A/C Evaporator Temperature Circuit High Input
P0538 2009 Ford Fusion — A/C Evaporator Temperature Circuit High Input
P0538 2010 Ford Fusion — A/C Evaporator Temperature Circuit High Input
P0538 2011 Ford Fusion — A/C Evaporator Temperature Circuit High Input
P0538 2012 Ford Fusion — A/C Evaporator Temperature Circuit High Input

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.