P0AAB: Hybrid/EV Battery Voltage Isolation Sensor Circuit Intermittent/Erratic
What to do
Note the weather when the warning appears. Appearing in the wet and clearing in the dry can mean marginal isolation rather than a flaky wire — say exactly that to the workshop, because the two get very different responses.
What this code means
The isolation measurement is cutting in and out — and this family's intermittent variant deserves one extra sentence of respect, because an erratic isolation reading has two candidate stories rather than one. The usual: a wiring fault in the measuring chain, tracked by bumps and damp like every intermittent in the block. The rarer but important one: genuinely marginal isolation that comes and goes with moisture — a leak path that only conducts when wet reads as an erratic sensor. A pattern that follows rain deserves the P0AA6 investigation, not just a connector check.
Likely causes
Start here
- Intermittent wiring fault · moderate
- Water ingress into connector · easy
Less common
- Water ingress into a high voltage connector · specialist
- Damaged high voltage cable insulation · specialist
Symptoms
Components involved
Information, not instruction
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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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