P0D90 is stored when the AC supplied to the on-board charger does not have a believable mains frequency. No official manufacturer document available to the public names the code with a threshold. A Ford patent on charger-to-EVSE detection describes the obvious method: after the pilot signal is present and S2 is closed, the charger measures the interval between successive zero passes of the incoming AC, increments an error counter whenever the result is under 40 Hz or over 70 Hz and stores a code after a set number of errors. The patent notes that the frequency fault need not stop charging, and that a frequency error together with a lost pilot is treated as the higher-ranking loss of AC power. Unstable sources such as small generators or faulty portable EVSEs are the usual trigger; often the driver notices nothing at all.
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
- Often no noticeable effect apart from the stored code
- Charging interrupted at certain supply points
Most likely causes
- Charging from a source with unstable frequency (small generator, inverter)
- Faulty portable charging unit or wall box
- Fault in the charger's frequency measurement
What to check, in order
Start with the simplest. You can tick off each step.
Good to know
- Repair difficulty: easy
What each character of P0D90 means
- P: Powertrain: engine and transmission
- 0: Generic code: same on every make
- D: Subsystem depends on the code range
- 90: Specific fault in that system
Frequently asked questions
Can I keep driving with code P0D90?
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 P0D90?
The most common causes are: charging from a source with unstable frequency (small generator, inverter); faulty portable charging unit or wall box; fault in the charger's frequency measurement.
Related codes
- P0D80Battery Charger Input Circuit/Open
- P0D81Battery Charger Input Circuit Range/Performance
- P0D27Battery Charger Input Voltage Too Low
- P0D28Battery Charger Input Voltage Too High
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.