U3509: The control unit input power C is below normal
The control unit input power C is below normal. It may be the control unit itself, its power supply or its connector.
| Code | U3509 |
|---|---|
| System | Communication network |
| Group | U35xx, Communication network |
| Type | Generic: it means the same on every make |
How to read and clear U3509 with Final OBD
Plug an OBD2 scanner in under the steering wheel, switch the ignition on and open Final OBD. Under Faults you’ll see U3509 with its description and whether it’s confirmed, pending or permanent.
If the engine stores it over standard OBD, with FREE you read this code with its explanation for nothing and clear it. With PRO you also read the faults of every control unit and clear them in all of them.
Clearing the code only turns the light off: if the cause is still there, it comes back. Clear it once it’s fixed, and not right before an inspection. It’s all in how to read and clear fault codes and in inspections and OBD.
Similar codes
- U3505 The control unit input power B is below normal
- U3506 The control unit input power B is above normal
- U3507 The control unit input power B fails now and then
- U3508 The control unit input power C gives readings outside the normal range
- U350A The control unit input power C is above normal
- U350B The control unit input power C fails now and then
- U350C The control unit cooling fan has a broken or disconnected wire
- U350D The control unit cooling fan gives a lower signal than normal
What does code U3509 mean?
The control unit input power C is below normal. It may be the control unit itself, its power supply or its connector.
How do you clear U3509?
With an OBD2 scanner and an app like Final OBD, which clears it for free if it’s stored by the engine control unit. But clearing it only turns the light off: if the cause isn’t fixed, U3509 comes back.
Read it on your car
Final OBD reads and clears engine faults through standard OBD for free, each one explained in plain English. With PRO it also reads the faults of every control unit, each make’s own codes included, and clears them in all of them.
