OBD Guide
ENFRDEESPT

P1B21

Hybrid/Electric Vehicle Battery 30 Circuit High Voltage

P1B21 is an OBD-II diagnostic trouble code meaning: Hybrid/Electric Vehicle Battery 30 Circuit High Voltage. Common causes: malfunction of the high-voltage battery management system, charger problems. Estimated repair cost: $167–889.

Severity
🔴 High
Can you drive?
Do not drive — repair immediately
Approx. repair cost
$167–889 (est.)

Symptoms

  • Check engine light comes on
  • Reduced vehicle power
  • The car goes into emergency mode
  • Problems with charging a high-voltage battery
  • Hybrid system warnings

Causes

  • Malfunction of the high-voltage battery management system
  • Charger problems
  • Degradation of high-voltage battery cells
  • Short circuit in high voltage circuit
  • Malfunction of voltage sensors

How to Fix

  1. Diagnose the high-voltage battery system
  2. Check the condition of the battery cells
  3. Check the operation of the battery management system
  4. Test the charger and related components
  5. Repair only from an authorized dealer

Related codes

P1B22P1B23P0AA6

FAQ

What does the P1B21 code mean?

P1B21 is an OBD-II diagnostic trouble code that indicates: Hybrid/Electric Vehicle Battery 30 Circuit High Voltage

What causes a P1B21 error code?

The most common causes of P1B21 include: Malfunction of the high-voltage battery management system; Charger problems; Degradation of high-voltage battery cells; Short circuit in high voltage circuit.

How do I fix a P1B21 diagnostic trouble code?

To fix P1B21: Diagnose the high-voltage battery system. Check the condition of the battery cells. Check the operation of the battery management system. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with P1B21?

Do not drive — repair immediately

How much does it cost to fix P1B21?

The estimated repair cost for P1B21 is $167–889. Actual cost depends on your vehicle, location, and labor rates.

FRDEESPT

See also: Russian version · NationStat