AutoCodes – Generic – P1003

P1003 Code - Fuel Composition Signals Message Counter Incorrect

Quick Answer

Control modules connected to the serial data circuits monitor the communication during normal vehicle operation. Common causes include Faulty Fuel Composition Sensor, Fuel Composition Sensor harness is open or shorted, Fuel Composition Sensor circuit poor electrical connection. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means: P1003 indicates Fuel Composition Signals Message Counter Incorrect.
Common causes: Common causes include Faulty Fuel Composition Sensor, Fuel Composition Sensor harness is open or shorted, Fuel Composition Sensor circuit poor electrical connection.
Severity: High - diagnose this code as soon as possible.
Can I drive?: Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

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Code Popularity 16,734

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on Aug 18, 2022

Description
Possible Causes
How To Fix
Cost to Diagnose
Comments
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Code P1003 Description

Control modules connected to the serial data circuits monitor the communication during normal vehicle operation. Operating information and commands are exchanged among the control modules. Each module on the serial data circuit maintains a transmit error counter and a receive error counter. The counter values increase with detected errors and decrease with error-free messages. The Diagnostic Trouble Code (DTC) will be set when the Fuel Composition Signals Message Counter Incorrect.

OBDII Code P1003 - Fuel Composition Signals Message Counter Incorrect - AutoCodes.com — P1003 Code - Fuel Composition Signals Message Counter Incorrect

What does this mean?

What are the Possible Causes of the DTC P1003?

Faulty Fuel Composition Sensor
Fuel Composition Sensor harness is open or shorted
Fuel Composition Sensor circuit poor electrical connection

How to Fix the DTC P1003?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P1003 code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

Need more information about the P1003 code?

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Need Help with the Code?

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Information for Specific Makes

P1003 Buick — Fuel Composition Signals Message Counter Incorrect
P1003 Cadillac — Fuel Composition Signals Message Counter Incorrect
P1003 Chevrolet — Fuel Composition Signals Message Counter Incorrect
P1003 GMC — Fuel Composition Signals Message Counter Incorrect

About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.