AutoCodes – BMW – P0603 BMW

P0603 BMW Code - ECM Self Check Fault

Quick Answer

Battery voltage is supplied to the ECM even when the ignition switch is turned OFF for the ECM memory function of the DTC memory, the air-fuel ratio feedback compensation value memory, the idle air volume learning value memory, etc. Common causes include Loose or poor battery terminal connection, Low battery charge, ECM power supply circuit is open or shorted. 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: P0603 BMW indicates ECM Self Check Fault.
Common causes: Common causes include Loose or poor battery terminal connection, Low battery charge, ECM power supply circuit is open or shorted.
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 7,088

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 Jun 14, 2020

Description
Step-by-Step Diagnostic Guide
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
FAQs
Comments
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Code P0603 BMW Description

OBDII Code P0603 BMW - ECM Self Check Fault - AutoCodes.com — P0603 BMW Code - ECM Self Check Fault

What does this mean?

What are the Possible Causes of the DTC P0603 BMW?

Loose or poor battery terminal connection
Low battery charge
ECM power supply circuit is open or shorted
ECM Programing
Faulty ECM

How to Fix the DTC P0603 BMW?

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 does this mean?

Code Tech Notes

Start by charging the vehicles battery and clean terminal, once the battery is charged and the terminals are clean and secure, erase code. If the code comes back ON you may have to reprogram or replaced ECM

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0603 BMW 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 P0603 BMW code?

Need more information on how to fix the P0603 BMW code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P0603 BMW code diagnosed by a professional: Find a repair shop in your area

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.

Frequently Asked Questions about P0603 BMW Code

1. What does the OBDII code P0603 mean on a BMW?

P0603 indicates an ECM Self Check Fault, which means the Engine Control Module (ECM) has detected an issue during its internal memory self-check process.

2. What are the common symptoms of the P0603 code in a BMW?

Symptoms may include the check engine light turning on, engine performance issues, difficulty starting the car, or intermittent stalling.

3. What causes the P0603 code in a BMW?

Common causes include a failing ECM, a low or weak battery, poor electrical connections, or improper programming or tuning of the ECM.

4. Can a weak battery cause the P0603 code in a BMW?

Yes, a weak or low-voltage battery can result in this code because the ECM relies on consistent power to perform its self-check.

5. How do you fix the P0603 code on a BMW?

Check and replace the battery if needed, inspect wiring and connectors for damage or corrosion, and reprogram or replace the ECM if necessary.

6. Is the P0603 code serious for a BMW?

While the car may still drive, the P0603 code can lead to performance issues and potential ECM failure, so it should be addressed promptly.

7. Can aftermarket tuning cause the P0603 code on a BMW?

Yes, improper or incomplete aftermarket tuning can disrupt the ECMâ€™s programming and trigger this fault code.

8. How much does it cost to fix the P0603 code on a BMW?

Costs vary depending on the issue, ranging from $100 for a battery replacement to over $1,000 if the ECM needs replacing.

9. Can you clear the P0603 code without repairs?

You can clear the code with an OBDII scanner, but if the underlying issue isnâ€™t resolved, it will likely return.

10. How can you prevent the P0603 code on a BMW?

Maintain a healthy battery, ensure proper ECM programming, and avoid low-quality aftermarket parts or tuning. Regular maintenance checks can also help prevent this issue.