P1A21
Hybrid Battery Contactor Control Sequence Incorrect
P1A21 is an OBD-II diagnostic trouble code meaning: Hybrid Battery Contactor Control Sequence Incorrect. Common causes: faulty hybrid battery contactors, problems with the wiring harness to the contactors. Estimated repair cost: $50–167.
Symptoms
- Hybrid system does not activate
- Hybrid system warning light on dashboard
- Reduced power or complete loss of traction
- The car goes into emergency mode
- Clicking or other unusual sounds coming from the engine compartment
Causes
- Faulty hybrid battery contactors
- Problems with the wiring harness to the contactors
- Problems with the hybrid system control module
- Hybrid battery low
- Corrosion or poor contact in control circuit
How to Fix
- Checking the condition of the hybrid battery contactors
- Diagnostics of control circuits and power supply of contactors
- Checking fault codes in the hybrid system control module
- Replacing faulty contactors or repairing wiring
- Hybrid System Software Update
Related codes
FAQ
What does the P1A21 code mean?
P1A21 is an OBD-II diagnostic trouble code that indicates: Hybrid Battery Contactor Control Sequence Incorrect
What causes a P1A21 error code?
The most common causes of P1A21 include: Faulty hybrid battery contactors; Problems with the wiring harness to the contactors; Problems with the hybrid system control module; Hybrid battery low.
How do I fix a P1A21 diagnostic trouble code?
To fix P1A21: Checking the condition of the hybrid battery contactors. Diagnostics of control circuits and power supply of contactors. Checking fault codes in the hybrid system control module. For a complete diagnosis, use an OBD-II scanner.
Is it safe to drive with P1A21?
Do not drive — repair immediately
How much does it cost to fix P1A21?
The estimated repair cost for P1A21 is $50–167. Actual cost depends on your vehicle, location, and labor rates.
See also: Russian version · NationStat