P0D90: Battery Charger Input Frequency Incorrect
What to do
If you are charging from a generator, this is probably the generator rather than the car — small engine-driven generators often cannot hold a steady enough frequency, regardless of their wattage. On mains power, try another charge point; if it happens everywhere, the car needs looking at.
What this code means
The frequency of the alternating-current supply is outside what the charger will accept.
This is the code that explains why a car will not charge from a generator, and it is worth knowing because the behaviour looks like faulty equipment on both sides.
A charger has to synchronise to the supply. It draws current in step with the incoming waveform, which means it must first work out what that waveform is doing — 50 hertz in most of the world, 60 in the Americas. Both are fine; what is not fine is a frequency that wanders.
And a generator's frequency is its engine speed. A portable generator holds its speed with a mechanical governor that reacts after the load changes, so every time the charger draws more current the engine dips and the frequency dips with it. The charger sees a supply it cannot lock onto and declines. Larger inverter-type generators regulate electronically and usually work; small governor-type ones frequently do not, whatever their power rating says.
So the useful question is what the car is plugged into. On grid power this code is rare and points at the charge point or the car's input sensing. On generator power it is close to expected, and the answer is a different generator rather than a repair.
Likely causes
Start here
Less common
- Faulty on-board charger · specialist
- Corroded or loose connector · specialist
Rare
- Damaged wiring harness · specialist
- Damaged charging inlet or pins · moderate
Symptoms
Components involved
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
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What makes one worth reading:
- The car — make, model, year and engine. The same fault behaves differently on each.
- What you measured, not only what you replaced.
- What actually fixed it — or that nothing did, which is worth knowing too.
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