What it means
Battery charger A output voltage is below the expected range. Charging operation may be affected.
How it works
Battery charger A converts incoming charging power into output for the vehicle's battery system. P0D21 sets when the module measures charger A output below its expected range, which can prevent charging from starting, interrupt it, or reduce the charge rate.
Common causes
Most likely first.
- Battery charger fault
- Charging circuit or connection fault
Symptoms
- Charge status indicator shows fault
- Charging may not start or interrupts
- Slower-than-expected charge rate
How to diagnose it
- Read freeze-frame and charging live data to confirm charger A's measured output is low and note the charging conditions when it occurred.
- Check whether the fault repeats with another approved charging source or cable, then inspect the inlet and connectors for incomplete seating or visible damage.
- With the vehicle powered down as specified by the manufacturer, inspect charger A's wiring and connections for corrosion, looseness, or heat damage.
- Test the charging circuit for excessive resistance or a connection fault using the wiring diagram and manufacturer's procedure.
- If the input and circuit connections meet specification but charger A output remains low, perform the manufacturer's charger output test.
Common fixes
- Reseat or replace a faulty external charging cable or connector.
- Clean or repair a high-resistance connection in charger A's circuit.
- Repair damaged charging-circuit wiring.
- Replace charger A if its output remains below specification during testing.
Can I keep driving?
Do not rely on the vehicle for a long trip until it can charge reliably, and avoid repeated charging attempts if the vehicle reports a charging fault. Stop charging if you notice heat damage or receive a charging safety warning.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.