Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
This code means that the car's computer can't store important security information needed to start the car. It's like trying to save a game on a video game console, but there's no space left to save it.
The Electronic Immobilizer system is responsible for ensuring that the vehicle can only be started with the correct key. This code indicates that there is an issue with storing necessary data in the immobilizer system.
The P165C code is triggered when the vehicle's Electronic Immobilizer System (EWS) detects that it cannot store necessary data. This could be due to memory issues or communication problems between the EWS and other control modules.
• Engine fails to start
• Security light on the dashboard
• Intermittent starting issues
• Faulty Electronic Immobilizer System
• Corrupted data in the EWS module
• Communication errors between EWS and other modules
EWS: Electronic Immobilizer System
ECU: Engine Control Unit
• Check for other related codes
• Inspect the EWS module for faults
• Test communication lines between EWS and ECU
• Reprogram the EWS module
• Replace faulty EWS components
• Clear any corrupted data from the system
• OBD-II scanner
• Multimeter
• Diagnostic computer with reprogramming capability
$150 - $500
Moderate
• BMW 3 Series
• BMW 5 Series
• BMW X5
• Regularly update vehicle software
• Avoid aftermarket key programming
• Ensure proper battery maintenance
Security System Issue
• Avoid using non-OEM keys
• Have the vehicle regularly serviced
• Consult a professional for key programming
Check with the vehicle manufacturer for warranty coverage on security system components.
This code has been more prevalent in vehicles with complex electronic security systems, especially in models with aging EWS components.
High – This issue can prevent the vehicle from starting, leaving you stranded.
Ensure all repairs are conducted by certified professionals to maintain vehicle security and warranty.
• Vehicle in ignition mode
• Attempt to start the engine
The EWS module is typically located under the dashboard near the steering column.
Q: Can I fix this code myself?
A: It's recommended to have a professional handle this issue due to the complexity of the immobilizer system.
Q: Will this code cause my car to stop working?
A: Yes, this code can prevent the car from starting, so it should be addressed promptly.
Pro · Four-system diagnostics
A handheld scanner aimed at engine, transmission, ABS, and airbag diagnostic work.
Chassis and ABS faults usually need a scanner that can read brake-system data directly.
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Universal · Torque wrench
Useful when reassembly torque matters for wheel, suspension, and under-hood fasteners.
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Helpful for safer access underneath the vehicle during exhaust, EVAP, and underbody inspection work.
Helpful for safer access during underbody inspection work.
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