Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
The car's computer is having trouble talking to the system that helps keep the car stable and prevent skidding.
The Controller Area Network (CAN) is not receiving a signal from the ASC/DSC module, which is responsible for stability control.
The P1721 code indicates a communication error on the CAN bus between the Engine Control Module (ECM) and the Active Stability Control (ASC) or Dynamic Stability Control (DSC) module. This can be due to a lack of signal or a timeout condition.
• Stability control warning light on
• Loss of stability control functions
• Intermittent vehicle handling issues
• Faulty ASC/DSC module
• Wiring issues in the CAN bus
• Faulty ECM
CAN: Controller Area Network, a robust vehicle bus standard designed to allow microcontrollers and devices to communicate with each other.
ASC/DSC: Active Stability Control/Dynamic Stability Control, systems that help maintain vehicle stability.
• Check for additional codes that may indicate a wiring issue.
• Inspect the CAN bus wiring and connectors for damage.
• Test the ASC/DSC module for proper operation.
• Repair or replace damaged wiring or connectors.
• Replace the ASC/DSC module if faulty.
• Reprogram or replace the ECM if necessary.
• OBD-II scanner
• Multimeter
• CAN bus diagnostic tool
$200 - $800
Moderate
• BMW 3 Series
• BMW 5 Series
• Mini Cooper
• Regular maintenance checks on the vehicle's wiring.
• Ensure all software updates are performed.
• Avoid harsh driving conditions that may stress the stability control system.
Communication Issue
• Drive cautiously if stability control is compromised.
• Schedule a diagnostic check with a professional mechanic.
Check with the vehicle manufacturer for coverage on electronic control modules.
This code has been associated with communication issues in vehicles with advanced stability control systems since the early 2000s.
Moderate – While the vehicle can still be driven, the stability control system may not function properly.
Driving without a functioning stability control system can increase the risk of accidents, especially in adverse conditions.
• Vehicle stationary and ignition on.
• Use diagnostic tools to monitor CAN bus communication.
The ASC/DSC module is typically located near the vehicle's center console or under the hood, depending on the vehicle model.
Q: Can I drive my car with the P1721 code?
A: Yes, but be cautious as the stability control system may not work, which can affect handling.
Q: Will clearing the code fix the problem?
A: Clearing the code may temporarily remove the warning, but it won't fix the underlying issue.
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