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TuningBot DTC Database · v4.37.14

U3021 Control Module Wake - up Circuit B Performance

Generic (OBD-II) interpretation in the TuningBot DTC database.

U · NetworkSoftwareOBD2

What U3021 means

U3021
Control Module Wake - up Circuit B Performance Generic · software Data confidence 65%

The control module judged the Control Module Wake - up Circuit B behaviour implausible for the current operating conditions.

Symptoms

  • MIL illuminated
  • Symptoms depend on the affected internal function

Possible causes

  • Internal control module hardware fault
  • Control module supply voltage or ground fault
  • Software/coding fault after programming
  • In rare cases, interference from wiring faults

Recommended checks

  • Check control module power supplies and grounds first
  • Check battery condition and charging voltage
  • Verify software version and check OEM bulletins
  • Clear the code and retest under the original conditions
  • Only after supply-side checks, consider module assessment

Related and nearby codes

U30 range
U3000U3001U3002U3003U3004U3005U3006U3007U3008U3009U300AU300BU300CU300DU300EU300FU3010U3011

How to read U3021

U

Network: communication between control units.

3

Generic SAE-standard code: same meaning on every make.

021

Specific fault index within the subsystem.

Frequently asked questions about U3021

What does U3021 mean?

Control Module Wake - up Circuit B Performance. The control module judged the Control Module Wake - up Circuit B behaviour implausible for the current operating conditions.

Is U3021 generic or manufacturer-specific?

U3021 is a generic OBD-II code: it has the same meaning on every make and model that follows the SAE standard.

Can TuningBot remove U3021 at file level?

Not guaranteed. Powertrain (P) codes can be reliably disabled in the ECU calibration, but body, chassis and network codes depend on the specific control unit and how the fault is implemented - some can be handled, some cannot. Ask for a quote and our engineers will check your file and tell you, free of charge, whether U3021 is removable in your case.

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