Fault-code directory · EV and hybrid diagnostic enquiries
High-voltage contactors connect and isolate the battery as part of normal vehicle control. A warning that refers to a contactor can prevent driving or charging. It needs a controlled assessment rather than repeated resets or an attempt to bypass the protection.
Codes covered
P0AA0 · P0AA1 · P0AA2 · P0AA3 · P0AA4 · P0AA5
The P0AA0–P0AA5 group distinguishes positive and negative battery-contactor circuit reports and reported stuck-open or stuck-closed states. The code records the controller’s conclusion from its monitoring. Confirmation still depends on the vehicle’s specified tests and supporting data.
Confirm the full description, suffix and reporting module for your vehicle. These are diagnostic starting points, not a parts replacement list.
Evidence that helps narrow the fault
- Keep all associated warnings and note whether the vehicle can charge, become ready or support its low-voltage systems. Do not experiment with repeated start attempts if the vehicle instructs you to stop.
- Record recent battery, collision, charging or software work. A changed component or incomplete commissioning can be relevant to the diagnostic sequence.
- Have the contactor state assessed with the related voltage and control information. The whole sequence matters more than a single isolated parameter.
Choosing the next repair step
The appropriate repair may concern the control path, contactor assembly or a wider system condition. The assessment must also establish that the vehicle can isolate correctly after the repair. High-voltage access and live measurements are specialist tasks, not owner checks suggested by this guide.
Can a contactor code be ignored if the car starts again?
An intermittent return to normal does not prove a safe or reliable repair. Preserve the event details and arrange assessment, following any stop or recovery instructions displayed by the vehicle.
Talk through the fault with AXION
Send the make, model, year, full scan report and a short description of when the fault happens. Include recent repairs or programming attempts. If you do not have a scan, describe the symptoms in your own words.
Workshop assessments are arranged by appointment in Didcot, Oxfordshire. UK-wide postal module testing and remote support are available for suitable work after compatibility and scope are agreed. Please contact us before removing or posting a module.
Assessment options and appointments · Garage and trade support
Related reading
- Hybrid battery temperature sensor codes with reduced performance
- EV battery current sensor codes and inconsistent charging data
Reference for generic code terminology: Snap-on diagnostic code reference. HSE guidance on electric and hybrid vehicle work. This article provides general diagnostic guidance and is not a report of a particular customer repair.