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 a part of the car's computer system isn't talking to another part like it should. Imagine if two friends stopped talking to each other and couldn't share important information.
The P1720 code indicates a communication issue between modules on the Controller Area Network (CAN) bus, specifically a timeout error.
The P1720 code is triggered when the Engine Control Module (ECM) or another control module on the CAN bus does not receive a signal from a specific module within the expected time frame. This can occur due to a fault in the wiring, a malfunctioning module, or a network issue.
• Check Engine Light illuminated
• Intermittent or complete loss of certain vehicle functions
• Erratic vehicle behavior
• Faulty control module
• Damaged or corroded wiring
• Loose or poor connections in the CAN bus network
CAN: Controller Area Network, a vehicle bus standard designed to allow microcontrollers and devices to communicate with each other.
ECM: Engine Control Module, a type of electronic control unit that manages engine performance.
• Use an OBD-II scanner to confirm the code and check for other related codes.
• Inspect the CAN bus wiring and connectors for damage or corrosion.
• Test the suspected control module for proper operation.
• Repair or replace damaged wiring or connectors.
• Replace the faulty control module if necessary.
• Clear the code and test drive the vehicle to ensure the issue is resolved.
• OBD-II scanner
• Multimeter
• Wiring repair kit
$100 - $1000, depending on the issue
Moderate
• Nissan Altima
• Infiniti G35
• Subaru Outback
• Regularly inspect and maintain vehicle wiring.
• Ensure all software updates are applied to control modules.
• Avoid exposure to moisture and corrosive elements.
Communication Issue
• Do not ignore the Check Engine Light.
• Consult a professional mechanic for diagnosis and repair.
Check with the vehicle manufacturer for warranty coverage on control modules.
This code has been more prevalent in vehicles with complex electronic systems and CAN bus networks.
Moderate – While the vehicle may still operate, certain functions may be impaired.
Driving with a malfunctioning control module may lead to unsafe vehicle operation.
• Vehicle parked with ignition on.
• Engine running at idle.
The control module is typically located in the engine bay or under the dashboard, depending on the vehicle model.
Q: Can I drive with a P1720 code?
A: It's not recommended as it may affect vehicle performance and safety.
Q: How do I reset the P1720 code?
A: After repairs, use an OBD-II scanner to clear the code from the vehicle's memory.
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.
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