U3542 code meaning
High Voltage System Interlock Circuit O Performance
Network system Generic code U35xx codes Check engine light
What U3542 means
U3542 marks loop O as implausible. Interlock trouble often clusters around charging. Mercedes bulletin LI54.10-P-067823 for the third-generation smart electric drive with the optional 22 kW on-board charger, built before 25 March 2013, links sporadic or permanent interlock codes (P0A0A00, P0A0E00), a no-start with a charging-cable message and a battery that will not charge to loose low-voltage contacts at that charger. Technicians push or pull those plugs gently and wait up to 5 seconds each time to see whether charging begins; the fault may appear solely with cold or warm components. No maker documents U3542.
U3542 at a glance
- Check engine lightYes, usually on
- Emissions testNot an emissions code
- Limp modePossible
- Repair difficultyHard
- Typical labor0.5 to 4 hours
- Clears after repairWhen cleared with a scanner
Symptoms of U3542
- Vehicle will not start and reports a plugged-in charging cable
- Charging does not start or stops
- Fault at the beginning or end of a charging session
Common causes of U3542
- Most likelyLoose low-voltage contact at the on-board charger carrying loop O
- PossibleContact that opens only when components are hot or cold
- Less likelyInternal fault in the on-board charger
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Hvil loop oOn board charger
What each part of U3542 means
| U | Network system: communication between the control modules (CAN bus). |
| 3 | Reserved range, usually generic. |
| 42 | The exact fault in that area. |
What to do next
- Note U3542 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 U3542
What does U3542 mean?
U3542 means "High Voltage System Interlock Circuit O Performance". U3542 marks loop O as implausible. It is a generic code, so it means the same on every make.
Is it safe to drive with U3542?
Drive gently and only to a workshop. With U3542 the car can go into limp mode (reduced power) to protect itself.
Will U3542 fail an emissions test?
U3542 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 U3542 to fix?
Difficulty: hard. A typical repair takes 0.5 to 4 hours of work. This is a job for a workshop.
Will U3542 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.