OBD Guide
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P1612

Chain of ECM-IMMU

P1612 is an OBD-II diagnostic trouble code meaning: Chain of ECM-IMMU. Common causes: open or short circuit in wiring harness, immobilizer malfunction. Estimated repair cost: $56–167.

Severity
🔴 High
Can you drive?
Yes, but get it checked soon
Approx. repair cost
$56–167 (est.)

Symptoms

  • Engine won't start
  • The immobilizer indicator is on
  • Check Engine light comes on
  • Intermittent engine operation before stopping

Causes

  • Open or short circuit in wiring harness
  • Immobilizer malfunction
  • Problems with the engine control unit
  • Software mismatch
  • Damaged connectors or corroded contacts

How to Fix

  1. Check the integrity of the wiring harness between the ECM and IMMU
  2. Inspect and clean connector contacts
  3. Check the power and ground of the immobilizer
  4. Read immobilizer fault codes
  5. Update or reflash ECM/IMMU software
  6. Repair only from an authorized dealer

Related codes

P1610P1611P1613

Error P1612 by Vehicle Brand

BuickCadillacChevroletGMGMCJaguarMercedes-BenzOldsmobileSaturnVolkswagen

FAQ

What does the P1612 code mean?

P1612 is an OBD-II diagnostic trouble code that indicates: Chain of ECM-IMMU

What causes a P1612 error code?

The most common causes of P1612 include: Open or short circuit in wiring harness; Immobilizer malfunction; Problems with the engine control unit; Software mismatch.

How do I fix a P1612 diagnostic trouble code?

To fix P1612: Check the integrity of the wiring harness between the ECM and IMMU. Inspect and clean connector contacts. Check the power and ground of the immobilizer. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with P1612?

Yes, but get it checked soon

How much does it cost to fix P1612?

The estimated repair cost for P1612 is $56–167. Actual cost depends on your vehicle, location, and labor rates.

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See also: Russian version · NationStat