P0D42 is the circuit code for the sensor that measures voltage at the 14 V output of the battery charger, a low-voltage DC stage built into the on-board charger and distinct from the vehicle's main DC/DC converter. GM's charger module in the Volt and ELR has such an output and monitors its voltage with P0D43-P0D45, yet no manufacturer publishes P0D42 itself. A Ford patent explains the purpose of such a stage: a small converter inside the charger keeps the 12 V bus supplied during charging, so the main contactors and the large converter can stay off. CARB requires circuit checks on inputs of this kind. A fault can leave the 12 V side unsupported while plugged in or interrupt charging; driving is not directly affected.
High severity. Can I keep driving?If the car still runs, drive as little as possible and go to a specialized repair shop. Do not touch the orange cables: they carry high voltage.
Symptoms
- 12 V battery discharges while the car is plugged in
- Charging is interrupted
Most likely causes
- Open or shorted voltage sense circuit of the charger's low-voltage stage
- Poor 12 V or ground connection at the charger
- Failed on-board charger electronics
What to check, in order
Start with the simplest. You can tick off each step.
What each character of P0D42 means
- P: Powertrain: engine and transmission
- 0: Generic code: same on every make
- D: Subsystem depends on the code range
- 42: Specific fault in that system
Frequently asked questions
Can I keep driving with code P0D42?
If the car still runs, drive as little as possible and go to a specialized repair shop. Do not touch the orange cables: they carry high voltage.
What causes code P0D42?
The most common causes are: open or shorted voltage sense circuit of the charger's low-voltage stage; poor 12 V or ground connection at the charger; failed on-board charger electronics.
Related codes
- P0D43Battery Charger 14 Volt Output Voltage Sensor Circuit Range/Performance
- P0D44Battery Charger 14 Volt Output Voltage Sensor Circuit Low
- P0D45Battery Charger 14 Volt Output Voltage Sensor Circuit High
- P0D46Battery Charger 14 Volt Output Voltage Sensor Circuit Intermittent/Erratic
- P0D47Battery Charger 14 Volt Output Current Sensor Circuit
- P0D5BBattery Charger 14 Volt Output Power Performance
Sources
Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.