OBD Guide
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C1AAC

Vehicle Information Unmatched

C1AAC is an OBD-II diagnostic trouble code meaning: Vehicle Information Unmatched. Common causes: vin code mismatch in modules, incorrect ecu programming. Estimated repair cost: $56–167.

Severity
⚠️ Medium
Can you drive?
Do not drive — repair immediately
Approx. repair cost
$56–167 (est.)

Symptoms

  • Check Engine Light Is On
  • Problems starting the engine
  • Disabling security systems

Causes

  • VIN code mismatch in modules
  • Incorrect ECU programming
  • Replacing components without flashing
  • Damage to the CAN bus wiring harness
  • Immobilizer malfunctions

How to Fix

  1. Check the VIN code matches in all modules
  2. Read all fault codes
  3. Check the condition of the CAN bus wiring harness
  4. Reprogram modules if necessary
  5. Check immobilizer operation

Related codes

B0001U0121U0155

FAQ

What does the C1AAC code mean?

C1AAC is an OBD-II diagnostic trouble code that indicates: Vehicle Information Unmatched

What causes a C1AAC error code?

The most common causes of C1AAC include: VIN code mismatch in modules; Incorrect ECU programming; Replacing components without flashing; Damage to the CAN bus wiring harness.

How do I fix a C1AAC diagnostic trouble code?

To fix C1AAC: Check the VIN code matches in all modules. Read all fault codes. Check the condition of the CAN bus wiring harness. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with C1AAC?

Do not drive — repair immediately

How much does it cost to fix C1AAC?

The estimated repair cost for C1AAC is $56–167. Actual cost depends on your vehicle, location, and labor rates.

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See also: Russian version · NationStat