U1021 Code - Lost Communication With Anti-Lock Brake System Control Module
Quick Answer
The Diagnostic Trouble Code (DTC) sets in the Powertrain Control Module (PCM) if data messages received from the Anti-Lock Brake System (ABS) Control Module over the HS-CAN2 is missing. Common causes include Faulty Anti-Lock Brake System (ABS) Control Module, Anti-Lock Brake System Control Module harness is open or shorted, Anti-Lock Brake System Control Module circuit poor electrical connection. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
- What it means
- U1021 indicates Lost Communication With Anti-Lock Brake System Control Module.
- Common causes
- Common causes include Faulty Anti-Lock Brake System (ABS) Control Module, Anti-Lock Brake System Control Module harness is open or shorted, Anti-Lock Brake System Control Module circuit poor electrical connection.
- Severity
- High - diagnose this code as soon as possible.
- Can I drive?
- Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
Code U1021 Description
What are the Possible Causes of the DTC U1021?
- Faulty Anti-Lock Brake System (ABS) Control Module
- Anti-Lock Brake System Control Module harness is open or shorted
- Anti-Lock Brake System Control Module circuit poor electrical connection
- Faulty Powertrain Control Module (PCM)
How to Fix the DTC U1021?
Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.
What is the Cost to Diagnose the Code?
Labor: 1.0
To diagnose the U1021 code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.
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Information for Specific Makes
- U1021 Ford — Lost Communication With Anti-Lock Brake System Control Module
- U1021 Lincoln — Lost Communication With Anti-Lock Brake System Control Module
- U1021 Mercury — Lost Communication With Anti-Lock Brake System Control Module
Frequently Asked Questions about U1021 Code
What does the OBDII code U1021 mean?
U1021 indicates a loss of communication between the vehicle's main computer (ECU) and the Anti-Lock Brake System (ABS) control module.
What are the common symptoms of code U1021?
Symptoms may include the ABS warning light turning on, loss of ABS functionality, erratic braking behavior, or other warning lights related to vehicle stability systems.
What causes the U1021 code to appear?
Common causes include a faulty ABS control module, damaged wiring or connectors in the ABS system, issues with the CAN bus network, or electrical interference.
Can U1021 affect braking performance?
Yes, if the ABS system is compromised, it could lead to reduced braking efficiency, especially during emergency stops or slippery road conditions.
How can I diagnose the U1021 code?
Start by using a scan tool to confirm the code, inspect the wiring and connectors for damage, check for other related codes, and test the ABS control module for proper operation.
Can I drive my car with the U1021 code?
While the vehicle may still be drivable, the ABS system may not function properly, increasing the risk of skidding or loss of control during hard braking or on slippery surfaces.
How do I fix the U1021 code?
Repairs may involve replacing the ABS control module, repairing damaged wiring or connectors, updating the vehicle’s software, or addressing any CAN bus communication issues.
What tools are needed to troubleshoot the U1021 code?
You may need an OBDII scan tool, a multimeter for testing electrical connections, and wiring diagrams to inspect the CAN bus network.
Is a U1021 code specific to one manufacturer?
No, U1021 is a generic communication code that can appear in various makes and models, though its implementation may vary slightly depending on the vehicle.
Can a weak battery cause U1021?
Yes, a weak or failing battery can cause voltage drops that disrupt communication between the ECU and ABS module, potentially triggering this code.
Discuss the causes and fixes for U1021 OBDII Code
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