P0ADD: Hybrid/EV Battery Negative Contactor Control Circuit/Open
What to do
As P0AD9 — twelve-volt battery first, then the coil wiring, and read companion codes as one fault until shown otherwise.
What this code means
The command wire to the negative contactor has failed open — P0AD9's fault on the other pole, with the same command-versus-confirmation logic and the same reading of companion codes: a stuck-open code alongside is the echo of this one, not a second fault.
Likely causes
Start here
- Open circuit in control wiring · moderate
- Corroded or loose connector · easy
Less common
- Failing 12 volt battery · easy
- Fault stored in the battery energy control module · 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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