Ambient/Battery Temperature Sensor Voltage Too Low (Chrysler)
What does P1493 mean?
The P1493 code means the vehicle's onboard diagnostic system has detected: Ambient/Battery Temperature Sensor Voltage Too Low (Chrysler). This is a low severity code.
Common Symptoms
- Check Engine Light illuminated
- Outside temperature display reads very high or erratic
- EVAP system monitors may not complete
- Slightly rich cold-start fuel mixture
- No significant drivability problems
Probable Causes (Ranked by Likelihood)
- Shorted ambient temperature sensor Very High
- Short to ground in the sensor wiring High
- Water intrusion in the sensor connector High
- Damaged wiring harness pinched against chassis Moderate
- PCM input circuit fault Low
Step-by-Step Diagnostic Procedure
-
Read the ambient temperature sensor value on a scan tool. A very high temperature reading when it is cool outside confirms the issue.
-
Inspect the sensor connector behind the front bumper for water intrusion or corrosion.
-
Measure sensor resistance. A reading near zero ohms indicates an internal short.
-
Check the wiring from the sensor to the PCM for shorts to ground, especially where it passes near the frame.
-
Disconnect the sensor and check if the PCM reads open circuit (maximum value). This confirms the wiring is not shorted.
Frequently Asked Questions
Why does low voltage mean high temperature reading?
The ambient temperature sensor is a negative temperature coefficient (NTC) thermistor. Its resistance decreases as temperature increases. A short circuit mimics very low resistance, which the PCM interprets as extremely high temperature.
Can road debris damage this sensor?
Yes. Because the sensor is mounted behind the front bumper, it is exposed to road splash, debris, and salt spray. Physical damage or water intrusion are common causes of failure.
Is the repair the same as for P1492?
The diagnostic approach is similar, but P1492 typically indicates an open circuit while P1493 indicates a short. The sensor location and testing procedures are the same.