OBD Guide

P21DC

Cylinder 1 Injector B Circuit High

P21DC is an OBD-II diagnostic trouble code meaning: Cylinder 1 Injector B Circuit High. Common causes: cylinder 1 injector malfunction, open or short circuit in the injector control circuit. Estimated repair cost: $17–89.

Severity
⚠️ Medium
Can you drive?
Limited driving only, diagnose soon
Approx. repair cost
$17–89 (est.)

Symptoms

  • Unstable engine operation
  • Increased fuel consumption
  • Misfire in cylinder 1
  • Difficulty starting the engine
  • Power Loss

Causes

  • Cylinder 1 injector malfunction
  • Open or short circuit in the injector control circuit
  • Poor contact in the injector connector
  • Engine control unit malfunction
  • Wiring harness damage

How to Fix

  1. Check the resistance of the injector of cylinder 1
  2. Inspect the injector wiring and connectors for damage.
  3. Check the voltage in the injector control circuit
  4. If necessary, replace the injector
  5. Update ECU firmware (if required)

Related codes

Error P21DC by Vehicle Brand

FAQ

What does the P21DC code mean?

P21DC is an OBD-II diagnostic trouble code that indicates: Cylinder 1 Injector B Circuit High

What causes a P21DC error code?

The most common causes of P21DC include: Cylinder 1 injector malfunction; Open or short circuit in the injector control circuit; Poor contact in the injector connector; Engine control unit malfunction.

How do I fix a P21DC diagnostic trouble code?

To fix P21DC: Check the resistance of the injector of cylinder 1. Inspect the injector wiring and connectors for damage.. Check the voltage in the injector control circuit. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with P21DC?

Limited driving only, diagnose soon

How much does it cost to fix P21DC?

The estimated repair cost for P21DC is $17–89. Actual cost depends on your vehicle, location, and labor rates.

See also: Russian version · NationStat