P1437 Lexus A/C Evaporator Air Temperature Circuit High

P1437 Lexus A/C Evaporator Air Temperature Circuit High

Possible causes
  • ACET circuit open.
  • SIG RTN circuit open to the ACET sensor.
  • ACET circuit short to power (VREF).
  • Damaged ACET sensor.
  • Damaged PCM.
    • Tech description
    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 cirucits (ACET or SIG RTN), which would cause the voltage to remain high. Although not as probable, also check for a short to power (VREF).
    Symptoms
    – Engine Light ON (or Service Engine Soon Warning Light)
    P1437 Lexus Description

    Indicates the ACET signal input was greater than the self-test maximum. The self-test maximum is 4.5 volts.

    Lexus Vehicle:Lexus ES,Lexus GS,Lexus GX,Lexus HS,Lexus IS,Lexus LFA,Lexus LS,Lexus LX,Lexus RX,Lexus RX,Lexus SC,Lexus GS350,Lexus GS450H,Lexus IS250,Lexus GX460,Lexus IS350,Lexus LS460,Lexus LS600H,Lexus LX570,Lexus RX350
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