OBD Guide
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P1003

Fuel Composition Signals Message Counter Incorrect

P1003 is an OBD-II diagnostic trouble code meaning: Fuel Composition Signals Message Counter Incorrect. Common causes: can bus break or damage, engine control module (ecu) malfunction. 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
  • Increased fuel consumption
  • Check Engine Light Illuminates
  • Reduced engine power
  • Problems starting the engine

Causes

  • CAN bus break or damage
  • Engine control module (ECU) malfunction
  • Problems with fuel composition sensors
  • Corrosion of contacts in the data transmission circuit
  • Software error in control module

How to Fix

  1. Check the integrity of the CAN bus
  2. Diagnose the engine control module
  3. Check the condition of the fuel composition sensors
  4. Clean contacts in the data circuit
  5. Update ECU firmware

Related codes

P1001P1002P1004

FAQ

What does the P1003 code mean?

P1003 is an OBD-II diagnostic trouble code that indicates: Fuel Composition Signals Message Counter Incorrect

What causes a P1003 error code?

The most common causes of P1003 include: CAN bus break or damage; Engine control module (ECU) malfunction; Problems with fuel composition sensors; Corrosion of contacts in the data transmission circuit.

How do I fix a P1003 diagnostic trouble code?

To fix P1003: Check the integrity of the CAN bus. Diagnose the engine control module. Check the condition of the fuel composition sensors. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with P1003?

Yes, but get it checked soon

How much does it cost to fix P1003?

The estimated repair cost for P1003 is $17–89. Actual cost depends on your vehicle, location, and labor rates.

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See also: Russian version · NationStat