What it means
The signal from the battery charger A input voltage sensor A is above the expected electrical range. The reading may be unreliable.
At a glance
- The engine or gearbox may go into limp mode
How it works
Battery Charger A monitors the voltage at its input through input voltage sensor A. The control module sets P0D40 when that sensor's signal is electrically higher than the expected range, so it cannot reliably judge the charger's input voltage.
Common causes
Most likely first.
- Signal wire shorted to B+
- Open sensor
- Connector pins corroded - high contact resistance
Symptoms
- Charge status indicator shows fault
- Charging may not start or interrupts
- Slower-than-expected charge rate
How to diagnose it
- Read freeze-frame data and live input-voltage-sensor A data to see when the high reading occurs and whether it is steady.
- With the vehicle powered down as specified by the manufacturer, inspect sensor A's connector and wiring for corrosion, loose pins, damage, or contact with a B+ wire.
- Check the sensor's supply, ground, and signal connections against the wiring diagram and manufacturer's specification.
- Test the signal wire for a short to B+ and check for an open sensor circuit using the manufacturer's procedure.
- If the wiring and connections pass, test input voltage sensor A and replace it only if its output is outside specification.
Common fixes
- Clean corroded connector pins and restore a sound connection.
- Repair a signal wire shorted to B+ or an open in the sensor circuit.
- Replace a failed battery charger A input voltage sensor A.
Can I keep driving?
Charging may fail to start, stop unexpectedly, or run slowly, and the vehicle may limit charging functions. Avoid relying on the charger until the fault is repaired; if this affects high-voltage charging, follow the vehicle's warnings and stop if they indicate an unsafe condition.
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.