AutoCodes – Generic – P1803

P1803 Code - Immobilizer ECU Signal Error

Quick Answer

P1803 indicates Immobilizer ECU Signal Error. Common causes include Faulty Immobilizer ECU, Immobilizer ECU harness is open or shorted, Immobilizer ECU 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: P1803 indicates Immobilizer ECU Signal Error.
Common causes: Common causes include Faulty Immobilizer ECU, Immobilizer ECU harness is open or shorted, Immobilizer ECU 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 12,727

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 Sep 20, 2019

Description
Possible Causes
How To Fix
Cost to Diagnose
Comments
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Code P1803 Description

OBDII Code P1803 - Immobilizer ECU Signal Error - AutoCodes.com — P1803 Code - Immobilizer ECU Signal Error

What does this mean?

What are the Possible Causes of the DTC P1803?

Faulty Immobilizer ECU
Immobilizer ECU harness is open or shorted
Immobilizer ECU circuit poor electrical connection

How to Fix the DTC P1803?

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 P1803 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 P1803 code?

Need more information on how to fix the P1803 code? Get Access to Factory Service Manuals

Need Help with the Code?

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Information for Specific Makes

P1803 Hyundai — Immobilizer ECU Signal Error
P1803 KIA — Immobilizer ECU Signal Error

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.