What this code means

The PCM detected that the 5-volt reference A circuit voltage is out of tolerance. This circuit provides the sensor feed voltage for multiple sensors including the MAP sensor, TP sensor, EGR valve position sensor, and fuel tank pressure sensor. A fault here can affect multiple systems simultaneously.

Symptoms

• Check Engine Light
• Engine stalling
• Rough idle
• Poor performance
• Multiple sensor codes may set
• Loss of power

Common causes

• Short to ground in one of the sensors connected to the 5V reference
• Damaged sensor wiring
• Faulty sensor drawing excessive current
• Defective PCM 5V reference driver
• Fuel pump harness shorted to fuel tank pressure sensor

Diagnostic steps

1. Measure 5V reference voltage at multiple sensors
2. Disconnect sensors one at a time to isolate short
3. Inspect fuel pump harness for shorts to FTP sensor
4. Check sensor wiring for chafing or damage
5. Test PCM 5V reference output

Repair notes

Disconnect sensors one at a time to find which sensor circuit is pulling the reference low. Inspect fuel pump harness. Repair shorted wiring. This is a root-cause code that can trigger many other sensor DTCs.

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