What P0A1B means
P0A1B flags a self-test failure of the processor that controls drive motor A, usually inside the inverter.
How the engine computer detects it
In GM hybrid tables (2016) it sets when the processor fails an inhibit path test at power-down, three or more times, proving it could not take the system to a safe state; in 2011 tables internal SPI, RAM or cache faults in 28 of 32 samples count. Both are Type A, MIL on the first trip. Land Rover sets P0A1B in the inverter of 2024-25 PHEVs at start-up, VW lists P0A1B00 for the ID.4 front drive. Toyota uses subtype P0A1B-1F on the 2023-24 Corolla Hybrid. Drive motor B is P0A1C. Expect a red loss-of-drive warning.
Written from public technical sources and not yet checked by a mechanic. How we write these pages
Symptoms
- Loss of drive warning and MIL
- Vehicle cannot be driven electrically or not at all
- Fault may vanish after a full sleep cycle while the code stays stored
Common causes
- Control software fault, several makers resolve it by reprogramming Most likely
- Internal processor or memory fault in the inverter control board Possible
- Weak 12 V supply during start-up or shutdown Less likely
How to diagnose P0A1B
- Read every stored code with an OBD-II scanner. If misfire or fuel trim codes are there too, fix those first: they often cause this one.
- Inspect the parts involved: drive motor a control module.
- Work through the causes above from most to least likely, cheapest checks first.
- Clear the code and drive a full drive cycle to confirm the repair held.
Reading the code
- P
- Powertrain
- 0
- Generic (SAE) code
- A
- Hybrid and electric propulsion
- 1B
- Specific fault
Questions drivers ask
Can I drive with code P0A1B?
If the car drives normally, drive gently to a shop that services hybrids. If it shows a hybrid system warning, loses power or won't go into Ready, pull over and have it towed. Never touch orange high-voltage cables.
Will my car pass an emissions inspection with P0A1B?
Probably not in states that test vehicles with an OBD-II scan: an emissions-related code that keeps the check engine light on is usually an automatic fail. Rules differ by state and county, so check yours.
This page is general information, not a substitute for a professional diagnosis. Repair costs are rough estimates for parts and labor and vary by vehicle and region.