DTC P0538: A/C Evaporator Temperature (ACET) Circuit High Input
WARNING: This page is about a different car, the 2006 Mercury Mariner and 2006 Ford Escape. However, it is still accessible from the selected car via links, so may be relevant.
P0538 - A/C EVAPORATOR TEMPERATURE (ACET) CIRCUIT HIGH INPUT
| Description: | Indicates the ACET signal input is greater than the self-test maximum. The self-test maximum is 4.5 volts. | ||
| Possible Causes: |
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| Diagnostic Aids: | The PCM sources a low current (5 volts) on the ACET circuit (this voltage can be measured with the sensor disconnected). As the A/C evaporator air temperature changes, the ACET circuit resistance to SIG RTN (ground) changes (which changes the voltage the PCM detects). When the ACET signal is detected above the self-test maximum, check for open circuits (ACET or SIG RTN), which cause the voltage to remain high. Although not as probable, also check for a short to power (VREF). | ||
| Application | Key On Engine Off | Key On Engine Running | Continuous Memory |
| All | GO to Pinpoint Test DJ . | ||