P0DAA: Battery Charging System Isolation Fault
What to do
Do not charge the car until it has been inspected, and treat this as urgent even though the car will probably drive normally. Isolation is what makes a high-voltage system safe to be near, and this says it has been compromised. If it appears in wet weather and disappears later, it has not fixed itself — report it anyway.
What this code means
The charging system has lost electrical isolation from the vehicle's chassis.
Isolation is the single design decision that makes a high-voltage car safe to touch, and this code says it has failed. A traction system is deliberately floating: neither of its poles is connected to the bodyshell, so touching one pole and the car does not complete a circuit through you. A 12-volt system does the opposite — it earths its negative to the body and returns current through the metal — which is exactly why the two cannot be reasoned about the same way. The argument is set out at P0D0E, and the monitoring that polices it at P0AA6.
What makes this code distinct is that it names the charging system. So the leak is somewhere in the path that only exists while the car is plugged in — the inlet, the charger, the charging contactors and their cabling — rather than in the pack or the drive system. That is a genuinely useful narrowing, and it comes with a most-likely cause attached: the charge inlet is the one high-voltage assembly on the car that is open to the weather and handled by hand, so water, salt and a cracked seal account for a large share of these.
Isolation faults are frequently intermittent and weather-dependent, appearing on wet mornings and clearing by afternoon, which is why one that clears itself must not be treated as one that fixed itself. A single isolation fault is not yet dangerous — that is the whole point of a floating system, since it takes two faults to make a path through a person. It is the loss of the safety margin, and the second fault is the one nobody sees coming.
Likely causes
Start here
- Water ingress into connector · specialist
- Damaged charging inlet or pins · moderate
- Damaged high voltage cable insulation · specialist
Less common
- Accident damage to high voltage components · specialist
- Faulty on-board charger · specialist
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
Be the first to write this up
Nothing posted about this yet. Whatever you found is worth writing down — even a dead end saves someone the same afternoon.
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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