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Code P1664

Symptoms

• Engine does not start

• Security light is illuminated on the dashboard

• Intermittent starting issues

Common Causes

• Faulty EEPROM in the EWS module

• Corrupted data in the EEPROM

• Wiring issues or poor connections to the EWS module

Glossary

EEPROM: Electrically Erasable Programmable Read-Only Memory

EWS: Electronic Immobilizer System

Related Codes

• P1663

• P1665

Official description

EWS (Electronic Immobilizer) Writing/Reading Error EEPROM

Laymans terms

This code means that the car's security system, which prevents it from being stolen, is having trouble reading or writing important information. It's like when your computer can't save or open a file properly.

Explanation

The P1664 code indicates a problem with the electronic immobilizer system's EEPROM, which is responsible for storing key data that allows the car to start.

Technical description

The EEPROM (Electrically Erasable Programmable Read-Only Memory) in the Electronic Immobilizer System (EWS) is used to store data related to the vehicle's security system. A P1664 code is triggered when there is a failure in reading or writing data to this memory, which can prevent the vehicle from recognizing the correct key and starting the engine.

Diagnosis steps

• Check for other related codes

• Inspect the wiring and connections to the EWS module

• Test the EEPROM for faults

Repair procedures

• Reprogram or replace the EEPROM

• Repair or replace faulty wiring

• Replace the EWS module if necessary

Tools required

• OBD-II scanner

• Multimeter

• EEPROM programmer

Estimated repair cost

$200 - $600

Difficulty level

Difficult

Commonly affected vehicles

• BMW 3 Series

• BMW 5 Series

• BMW X5

Preventive measures

• Regularly check and maintain the vehicle's electrical system

• Avoid exposing the vehicle to extreme temperatures

• Ensure the vehicle's battery is in good condition

Error code type

Security System Issue

User experience recommendations

• Do not attempt to start the vehicle repeatedly, as it may drain the battery.

• Consult with a professional mechanic or dealership for diagnosis and repair.

Warranty information

Check with the vehicle manufacturer for warranty coverage on the EWS module.

Historical data

This code has been more prevalent in older BMW models with the EWS system, particularly those manufactured in the late 1990s and early 2000s.

Urgency level

High – This issue can prevent the vehicle from starting, requiring immediate attention.

Legal and safety notice

Driving with a malfunctioning immobilizer system can leave the vehicle vulnerable to theft. Ensure repairs are conducted by a qualified technician.

Testing conditions

• Vehicle in a secure location

• Access to the EWS module

Component location

The EWS module is typically located under the dashboard on the driver's side or near the steering column.

FAQs

Q: Can I drive my car with a P1664 code?
A: No, this code usually means the car won't start, so it needs to be fixed before you can drive it.

Q: Is this a common issue?
A: It's relatively common in older BMW models with the EWS system, particularly if the vehicle has electrical issues.

Last updated: Mar 2, 2026 • Source: internal database
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