OBD Guide

P21C1

Cold Start Cylinder 12 Injection Timing

P21C1 is an OBD-II diagnostic trouble code meaning: Cold Start Cylinder 12 Injection Timing. Common causes: malfunction of the fuel injector of cylinder 12, problems with the fuel pump or pressure regulator. Estimated repair cost: $17–89.

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

Symptoms

  • Rough engine idling
  • Difficulty starting in cold weather
  • Increased fuel consumption
  • Loss of engine power
  • Dips during acceleration

Causes

  • Malfunction of the fuel injector of cylinder 12
  • Problems with the fuel pump or pressure regulator
  • Fuel system contamination
  • Malfunction of sensors (temperature, pressure)
  • Problems with the engine ECU

How to Fix

  1. Check the condition and operation of the injector of cylinder 12
  2. Diagnose the fuel system (pressure, fuel quality)
  3. Check the condition of the fuel filter
  4. Scan for other errors and sensor readings
  5. If necessary, replace faulty components

Related codes

Error P21C1 by Vehicle Brand

FAQ

What does the P21C1 code mean?

P21C1 is an OBD-II diagnostic trouble code that indicates: Cold Start Cylinder 12 Injection Timing

What causes a P21C1 error code?

The most common causes of P21C1 include: Malfunction of the fuel injector of cylinder 12; Problems with the fuel pump or pressure regulator; Fuel system contamination; Malfunction of sensors (temperature, pressure).

How do I fix a P21C1 diagnostic trouble code?

To fix P21C1: Check the condition and operation of the injector of cylinder 12. Diagnose the fuel system (pressure, fuel quality). Check the condition of the fuel filter. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with P21C1?

Limited driving only, diagnose soon

How much does it cost to fix P21C1?

The estimated repair cost for P21C1 is $17–89. Actual cost depends on your vehicle, location, and labor rates.

See also: Russian version · NationStat