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Lights the check engine lamp
U3556: Hydrogen Tank C Valve Control Circuit
Standardized SAE J2012 code · U35xx codes
What does U3556 mean?
Hydrogen Tank C Valve Control Circuit: the control circuit has an electrical fault.
The code tells you which monitor failed, not which part is broken. Test before replacing parts.
Symptoms
- Multiple warning lights may illuminate
- Affected modules may go into limp mode or shut down
- Specific functions inoperative depending on module
- Diagnostic tools may show communication faults
Common causes
- High Valve solenoid failed
- Low Gateway module routing CAN messages incorrectly
- Low CAN terminating resistor (120 Ω) drifted out of spec
Likelihood is a general estimate across vehicles; your make and model may differ.
Add your car to see reports of U3556 on the same make and model first.
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