U353F code meaning
High Voltage System Interlock Circuit N Low
Network system Generic code U35xx codes Check engine light
What U353F means
U353F covers a loop N value under the permitted minimum. The defect can sit inside a consumer rather than in the harness. For the Cummins battery electric systems BES CM2450 EV110B and EV111B, bulletin TSB250044 ties fault codes 8174 (interlock level too low or grounded) and 8175 to the electric air compressor: once the interlock contacts of the HV cable to the compressor pass, the measurement moves to the interlock pins of its low-voltage connector, and above 2 ohms (1 ohm in the first issue of February 2025) the compressor gets replaced. No maker documents U353F. While it is set, the vehicle is likely to lose high-voltage readiness.
U353F at a glance
- Check engine lightYes, usually on
- Emissions testNot an emissions code
- Limp modePossible
- Repair difficultyHard
- Typical labor1 to 6 hours
- Clears after repairWhen cleared with a scanner
Symptoms of U353F
- High voltage switches off and stays off
- Interlock fault returns although all cable plugs test fine
- Auxiliary drive such as the air compressor not running
Common causes of U353F
- Most likelyInterlock path inside an HV consumer such as an electric air compressor open or high-resistance
- PossibleHV cable plug on loop N not reconnected properly
- PossibleLoop N wire shorted to ground
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Hvil loop nHvil wiring
What each part of U353F means
| U | Network system: communication between the control modules (CAN bus). |
| 3 | Reserved range, usually generic. |
| 3F | The exact fault in that area. |
What to do next
- Note U353F and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about U353F
What does U353F mean?
U353F means "High Voltage System Interlock Circuit N Low". U353F covers a loop N value under the permitted minimum. It is a generic code, so it means the same on every make.
Is it safe to drive with U353F?
Drive gently and only to a workshop. With U353F the car can go into limp mode (reduced power) to protect itself.
Will U353F fail an emissions test?
U353F is not an emissions code, so on its own it usually does not fail an emissions test. Other stored codes or a lit check engine light still can.
How hard is U353F to fix?
Difficulty: hard. A typical repair takes 1 to 6 hours of work. This is a job for a workshop.
Will U353F clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.