What Does P1657 Mean?
The PCM has detected that the air conditioning clutch relay control circuit has voltage present when it should not, indicating a short to battery positive. This can cause unwanted A/C compressor engagement or prevent proper control.
Common Causes
35%
Wiring harness damaged with short to power wire in A/C clutch circuit
30%
Failed A/C clutch relay with stuck closed contacts
20%
Incorrectly wired aftermarket accessories or previous repair
15%
PCM internal driver circuit failure
Diagnostic Steps
1
Step 1: Remove A/C clutch relay and check if voltage remains on PCM control circuit (should drop to zero)
2
Step 2: Inspect relay socket and wiring for crossed wires, damaged insulation, or improper connections
3
Step 3: Disconnect A/C compressor clutch connector and check for unwanted voltage on control circuit
4
Step 4: Trace control wire from PCM to relay checking for contact with hot circuits or damaged insulation
5
Step 5: If no external short found, test PCM driver circuit for internal short or stuck-on output
Estimated Repair Cost
$100 - $500
Parts + labor, varies by vehicle and location
The PCM has detected that the air conditioning clutch relay control circuit has voltage present when it should not, indicating a short to battery positive. This can cause unwanted A/C compressor engagement or prevent proper control.
The most common cause of P1657 (A/C clutch relay circuit short to B+) is: Wiring harness damaged with short to power wire in A/C clutch circuit
Typical repair costs for P1657 range from $100 to $500, depending on the vehicle, location, and whether you do it yourself or go to a shop.
A/C compressor may run continuously causing excessive fuel consumption and potential compressor damage. No immediate safety concern but may affect engine performance.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P1657 to identify the root cause.
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Quick Info
Category
Powertrain
System
Air Conditioning System
Difficulty
Type
Manufacturer
Recommended Tools
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