What it means
The high-voltage system interlock circuit A reports a performance condition. Safety interlock chain may be compromised.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
The high-voltage interlock chain uses a monitored signal to confirm that protected connectors and access points are secure. P0A0B indicates that interlock circuit A is present but its behavior is outside the expected performance range, such as a signal that drifts or a contact that adds resistance.
Common causes
Most likely first.
- Interlock signal drifted
- High-resistance contact in interlock chain
Symptoms
- Hybrid system warning light on
- Vehicle may not enter READY mode
- Possible reduced or unavailable hybrid power
How to diagnose it
- Record freeze-frame data and scan all hybrid modules for related interlock or communication codes before clearing anything.
- Check scan-tool interlock circuit A status while the vehicle is in the conditions recorded in freeze-frame data, if those conditions can be reproduced safely.
- Inspect accessible interlock connectors and the service connector for incomplete seating, corrosion, damaged terminals, or signs of moisture.
- Check accessible interlock wiring for abrasion or strain that could cause resistance changes, without disconnecting or probing high-voltage components.
- Have a qualified technician test circuit A signal stability and contact resistance against the manufacturer's procedure after the high-voltage system is made safe.
Common fixes
- Correct a connector that is not fully seated using the specified safety procedure.
- Clean or replace a corroded low-voltage interlock terminal if the manufacturer's service information permits it.
- Repair damaged interlock wiring or replace a connector with unreliable contact.
- Replace a confirmed faulty interlock component after circuit testing.
Can I keep driving?
Because an interlock performance fault can cause hybrid power to drop out or prevent READY mode, avoid trips where loss of propulsion would be hazardous. Have the interlock checked promptly and do not touch high-voltage parts.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.