U3538High Voltage System Interlock Circuit L High
- Generic OBD-II code · Network
- Turns on the check-engine light
- Can trigger limp mode
- How the car detects it
- U3538 is stored when loop L overshoots its permitted maximum. In a constant-current loop that can be a contact problem rather than foreign voltage. Tesla's Model S tech note records its most frequent HVIL field failure as high-voltage plugs serving the cabin PTC heater, the heater for battery coolant and the A/C compressor harness whose interlock pins were too short: the supplier had changed the housing without lengthening the pins, and in the worst case male and female never met. Higher resistance raised the loop voltage until the fault set. Replacement plugs with longer pins carry a yellow dot. Comparable part revisions can matter on any loop L. No maker documents U3538; high voltage stays off.
- What you may notice
- Vehicle does not become ready or switches off high voltage
- Heating or air conditioning affected if their plugs are part of the loop
- Likely causes
- PossibleConnector revision in loop L with interlock pins too short for reliable contact
- PossibleLoop L wire in contact with a 12 V supply
- PossibleSpread female terminal in a loop L connector
- Repair
- Hard · Usually a job for a workshop.Typical cost: €80 – €1,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.