U3021
Control Module Wake-up Circuit B Performance
U3021 is an OBD-II diagnostic trouble code meaning: Control Module Wake-up Circuit B Performance. Common causes: open or short circuit in wake-up circuit, oxidation of connector contacts. Estimated repair cost: $17–89.
Symptoms
- Difficulty starting the engine
- Periodic shutdown of electronic systems
- Check Engine Light Is On
- Unstable operation of on-board electronics
- Errors in other modules
Causes
- Open or short circuit in wake-up circuit
- Oxidation of connector contacts
- Faulty wake up relay
- Wiring harness damage
- Internal control unit fault
How to Fix
- Check the integrity of the wake-up circuit wiring
- Clean connector contacts from oxidation
- Check relay functionality
- Scan other modules for errors
- If necessary, replace the control unit
Related codes
Error U3021 by Vehicle Brand
FAQ
What does the U3021 code mean?
U3021 is an OBD-II diagnostic trouble code that indicates: Control Module Wake-up Circuit B Performance
What causes a U3021 error code?
The most common causes of U3021 include: Open or short circuit in wake-up circuit; Oxidation of connector contacts; Faulty wake up relay; Wiring harness damage.
How do I fix a U3021 diagnostic trouble code?
To fix U3021: Check the integrity of the wake-up circuit wiring. Clean connector contacts from oxidation. Check relay functionality. For a complete diagnosis, use an OBD-II scanner.
Is it safe to drive with U3021?
Limited driving only, diagnose soon
How much does it cost to fix U3021?
The estimated repair cost for U3021 is $17–89. Actual cost depends on your vehicle, location, and labor rates.
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