P0D21: Battery Charger A Output Voltage Too Low

P0D21 is set when the high-voltage output of the on-board charger stays below what the controller expects. GM's Volt and ELR tables split the test in two: during normal charging the charger bus must not fall under 150 V, and when the charger only powers the battery heater, the bus must reach at least 75 % of an expected value calculated from charger current times 70 ohms. Eight failures in ten samples store it as Type B, lighting the MIL on the second trip. Stellantis stores P0D21-00 in the integrated dual charging module (IDCM) of the Jeep Wrangler 4xe from 2021, the Grand Cherokee 4xe from 2022 and the Pacifica Plug-in Hybrid from 2022, with MIL and no charging, and reflashes the IDCM. P0D20 covers a deviation in constant-voltage mode, P0D85 excess voltage.

Symptoms

• Vehicle does not charge
• MIL, often after two charging trips
• Battery not preheated while plugged in during cold weather

Most likely causes

• Charger module software (Stellantis IDCM bulletins)
• Failing power stage inside the charger
• High resistance or fault in the charger's high-voltage output path or heater load

What to check, in order

Start with the simplest. You can tick off each step.

1. Read the codes with a hybrid-compatible scanner and write down the freeze frame data
2. With the connector unplugged, check whether the signal wire is making contact with ground.
3. Make sure the battery cooling air intake is clean
4. Check the 12 V auxiliary battery, which can also trigger warnings
5. Leave any high-voltage measurements to a specialized repair shop

What each character of P0D21 means

• P: Powertrain: engine and transmission
• 0: Generic code: same on every make
• D: Subsystem depends on the code range
• 21: Specific fault in that system

Frequently asked questions

Can I keep driving with code P0D21?

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 P0D21?

The most common causes are: charger module software (Stellantis IDCM bulletins); failing power stage inside the charger; high resistance or fault in the charger's high-voltage output path or heater load.

Related codes

• P0D20Battery Charger A Output Voltage Performance
• P0D85Battery Charging Output Voltage Too High
• P0D4EBattery Charger Hybrid/EV Battery Output Voltage Sensor Circuit Low
• P2E3BBattery Charger B Output Voltage Too Low

Sources

• gsi.ext.gm.com: 12OBDG01A HYBRID Diagnostics
• gsi.ext.gm.com: 16OBDG01 Hybrid Diagnostics
• static.nhtsa.gov: MC 11034890 0001
• law.cornell.edu: 13 CCR 1968.2

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.