OBD Guide
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P12B4

Cylinder 1 Injection Timing Advance

P12B4 is an OBD-II diagnostic trouble code meaning: Cylinder 1 Injection Timing Advance. Common causes: malfunction of the fuel injector of cylinder 1, problems with the fuel pump. Estimated repair cost: $17–89.

Severity
⚠️ Medium
Can you drive?
Yes, but get it checked soon
Approx. repair cost
$17–89 (est.)

Symptoms

  • Unstable engine operation
  • Power reduction
  • Increased fuel consumption
  • Dips during acceleration
  • Check Engine light comes on

Causes

  • Malfunction of the fuel injector of cylinder 1
  • Problems with the fuel pump
  • Incorrect sensor readings (DPKV, DPRV)
  • Engine ECU malfunction
  • Problems with the injector wiring harness

How to Fix

  1. Check the condition of the fuel injector of cylinder 1
  2. Test the operation of the fuel pump
  3. Check the readings of the crankshaft and camshaft position sensors
  4. Diagnose the engine ECU
  5. Inspect the wiring harness to the injector for damage.

Related codes

P12B1P12B2P12B3

FAQ

What does the P12B4 code mean?

P12B4 is an OBD-II diagnostic trouble code that indicates: Cylinder 1 Injection Timing Advance

What causes a P12B4 error code?

The most common causes of P12B4 include: Malfunction of the fuel injector of cylinder 1; Problems with the fuel pump; Incorrect sensor readings (DPKV, DPRV); Engine ECU malfunction.

How do I fix a P12B4 diagnostic trouble code?

To fix P12B4: Check the condition of the fuel injector of cylinder 1. Test the operation of the fuel pump. Check the readings of the crankshaft and camshaft position sensors. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with P12B4?

Yes, but get it checked soon

How much does it cost to fix P12B4?

The estimated repair cost for P12B4 is $17–89. Actual cost depends on your vehicle, location, and labor rates.

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