OBD Guide

P21CF

Cylinder 1 Injector B Circuit/Open

P21CF is an OBD-II diagnostic trouble code meaning: Cylinder 1 Injector B Circuit/Open. Common causes: open or short circuit in the injector circuit, poor contact in the injector connector. Estimated repair cost: $17–89.

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

Symptoms

  • Unstable engine idling
  • Misfire in cylinder 1
  • Reduced engine power
  • Increased fuel consumption
  • Check Engine Light Is On

Causes

  • Open or short circuit in the injector circuit
  • Poor contact in the injector connector
  • Malfunction of the injector itself
  • Problems with the engine control unit
  • Wiring harness damage

How to Fix

  1. Check the integrity of the wires to the injector of cylinder 1
  2. Inspect the injector connectors for oxidation or damage.
  3. Check injector resistance (compare with other cylinders)
  4. If necessary, replace the injector
  5. Check the power supply and control signal from the ECU

Related codes

Error P21CF by Vehicle Brand

FAQ

What does the P21CF code mean?

P21CF is an OBD-II diagnostic trouble code that indicates: Cylinder 1 Injector B Circuit/Open

What causes a P21CF error code?

The most common causes of P21CF include: Open or short circuit in the injector circuit; Poor contact in the injector connector; Malfunction of the injector itself; Problems with the engine control unit.

How do I fix a P21CF diagnostic trouble code?

To fix P21CF: Check the integrity of the wires to the injector of cylinder 1. Inspect the injector connectors for oxidation or damage.. Check injector resistance (compare with other cylinders). For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with P21CF?

Limited driving only, diagnose soon

How much does it cost to fix P21CF?

The estimated repair cost for P21CF is $17–89. Actual cost depends on your vehicle, location, and labor rates.

See also: Russian version · NationStat