U3513 code meaning
High Voltage System Interlock Circuit B Low
Network system Generic code U35xx codes Check engine light
What U3513 means
U3513 reports a signal on interlock loop B that stays below its lower limit while the loop is energised by the module. What that means depends on the circuit: where the module feeds a test voltage in and reads it back at the far end, an opened plug reads low just like a wire touching ground. GM's documented loop A gives a sense of scale: its low code sets when less than 30 % of its 5 V check voltage comes back in two 12.5 ms samples, Type A. Texas Instruments' reference design shows how a current-fed loop can tell both apart: a grounded wire makes the loop current vanish while the supply current rises, with an open loop both drop. No maker publishes U3513. The contactors stay open; check loop B for chafed wires and unplugged connectors.
U3513 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 U3513
- No ready mode, HV contactors stay open
- Hybrid or EV warning lamp, MIL depending on maker
- Charging not possible
Common causes of U3513
- Most likelyInterlock wire of loop B chafed through to ground
- PossiblePlug or cover in loop B open, read as low by the sensing circuit
- PossiblePushed-back interlock terminal without contact
- Less likelyInterlock source in the monitoring module not delivering its signal
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Hvil loop bHvil wiring
What each part of U3513 means
| U | Network system: communication between the control modules (CAN bus). |
| 3 | Reserved range, usually generic. |
| 13 | The exact fault in that area. |
What to do next
- Note U3513 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 U3513
What does U3513 mean?
U3513 means "High Voltage System Interlock Circuit B Low". U3513 reports a signal on interlock loop B that stays below its lower limit while the loop is energised by the module. It is a generic code, so it means the same on every make.
Is it safe to drive with U3513?
Drive gently and only to a workshop. With U3513 the car can go into limp mode (reduced power) to protect itself.
Will U3513 fail an emissions test?
U3513 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 U3513 to fix?
Difficulty: hard. A typical repair takes 0.5 to 4 hours of work. This is a job for a workshop.
Will U3513 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.