Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
The car's security system is having trouble remembering the secret code it uses to start the car.
The Electronic Immobilizer System (EWS) uses a rolling code to ensure that only the correct key can start the car. A faulty storage error means the system is having trouble storing or recalling this code.
The P1655 code indicates an issue with the Electronic Immobilizer System's ability to store or recall the rolling code used for vehicle security. This can prevent the vehicle from starting as the system cannot verify the key's authenticity.
• Vehicle will not start
• Security warning light illuminated
• Intermittent starting issues
• Faulty immobilizer control unit
• Corrupted rolling code data
• Wiring issues in the immobilizer circuit
EWS: Electronic Immobilizer System
Rolling Code: A security code that changes each time it is used
• Check for other related codes
• Inspect immobilizer system wiring and connections
• Test the immobilizer control unit for faults
• Replace or reprogram the immobilizer control unit
• Repair or replace damaged wiring
• Update the vehicle's software if necessary
• OBD-II scanner
• Multimeter
• Diagnostic software
$150 - $500
Moderate
• BMW 3 Series
• BMW 5 Series
• Mini Cooper
• Regularly update vehicle software
• Avoid exposing key fobs to extreme temperatures
• Ensure all vehicle electrical connections are secure
Security System Issue
• Try using a spare key if available
• Avoid attempting to start the vehicle repeatedly
• Consult a professional if the issue persists
Check with your vehicle manufacturer for specific warranty coverage related to the immobilizer system.
This code is more common in vehicles with advanced security systems, particularly in European models.
High – This issue can prevent the vehicle from starting, requiring immediate attention.
Ensure any repairs or modifications to the immobilizer system comply with local laws and safety standards.
• Vehicle in 'on' position
• Key fob within range
The immobilizer control unit is typically located near the ignition switch or under the dashboard.
Q: Can I drive my car with a P1655 code?
A: No, this code can prevent your car from starting, making it undriveable.
Q: Will replacing the battery fix a P1655 code?
A: Not usually. This code is related to the immobilizer system, not the battery.
High-End · Full-system diagnostics
A full-system bidirectional platform aimed at advanced DIY users and professional diagnostic workflows.
Network faults often require full-system access instead of a generic code reader alone.
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Universal · Digital multimeter
A solid entry-level multimeter for voltage, continuity, resistance, and basic electrical troubleshooting.
Helpful for checking voltage drops, grounds, and basic circuit health when modules are not communicating.
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Universal · Wire connectors and repair kit
Useful when diagnosis points toward damaged wiring, corroded terminals, or connector repairs.
Useful if diagnosis points toward damaged connectors, wiring, or terminal repairs.
View on AmazonThese are optional diagnostic tools, not guaranteed fixes. As an Amazon Associate I earn from qualifying purchases.
Fitment Required · Vehicle-fitment part
Commonly relevant for misfire, ignition-efficiency, and some drivability-related repairs.
Misfire and ignition-related faults commonly involve spark plugs as part of the repair path.
Check the correct plug type, gap, and engine application for your vehicle.
View options on Amazon
Fitment Required · Vehicle-fitment part
Relevant when the fault points toward ignition-coil performance or cylinder-specific ignition issues.
Some ignition faults involve coil performance or cylinder-specific coil problems.
Match the coil to your engine and confirm the failed component before ordering.
View options on AmazonThese parts may be related to this fault category, but a code by itself does not confirm exact fitment or guarantee that replacing a part will solve the problem.