OBD Guide

P12B9

Cylinder 4 Injection Timing Related

P12B9 is an OBD-II diagnostic trouble code meaning: Cylinder 4 Injection Timing Related. Common causes: malfunction of the fuel injector of cylinder 4, problems with the injector electrical circuit. Estimated repair cost: $17–56.

Severity
⚠️ Medium
Can you drive?
Yes, but get it checked soon
Approx. repair cost
$17–56 (est.)

Symptoms

  • Unstable engine operation
  • Increased fuel consumption
  • Reduced engine power
  • Check Engine Light Illuminates
  • Misfire in cylinder 4

Causes

  • Malfunction of the fuel injector of cylinder 4
  • Problems with the injector electrical circuit
  • Incorrect signals from CKP or CMP sensors
  • Dirty or clogged nozzle
  • Problems with the engine control unit (ECU)

How to Fix

  1. Check the condition of the fuel injector of cylinder 4
  2. Check the electrical circuit of the injector for opens and shorts
  3. Check the operation of the CKP and CMP sensors
  4. Clean or replace fuel injector if necessary
  5. Check and update ECU software

Related codes

FAQ

What does the P12B9 code mean?

P12B9 is an OBD-II diagnostic trouble code that indicates: Cylinder 4 Injection Timing Related

What causes a P12B9 error code?

The most common causes of P12B9 include: Malfunction of the fuel injector of cylinder 4; Problems with the injector electrical circuit; Incorrect signals from CKP or CMP sensors; Dirty or clogged nozzle.

How do I fix a P12B9 diagnostic trouble code?

To fix P12B9: Check the condition of the fuel injector of cylinder 4. Check the electrical circuit of the injector for opens and shorts. Check the operation of the CKP and CMP sensors. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with P12B9?

Yes, but get it checked soon

How much does it cost to fix P12B9?

The estimated repair cost for P12B9 is $17–56. Actual cost depends on your vehicle, location, and labor rates.

See also: Russian version · NationStat