U3520
High Voltage System Interlock Circuit E High
U3520 is an OBD-II diagnostic trouble code meaning: High Voltage System Interlock Circuit E High. Common causes: open or short circuit in the interlock circuit, high voltage lockout sensor malfunction. Estimated repair cost: $56–278.
Symptoms
- The malfunction indicator on the dashboard lights up
- The car does not go into ready-to-drive mode
- Reduced power or complete loss of traction
- Inability to charge high voltage battery
Causes
- Open or short circuit in the interlock circuit
- High Voltage Lockout Sensor Malfunction
- Damage to the high voltage system wiring harness
- Problems with the high voltage system control module
- Corrosion of contacts in the interlock circuit
How to Fix
- Diagnose the high voltage interlock circuit
- Check the integrity of the wiring harness and contacts
- Test blocking sensors
- Replace damaged components if necessary
- Repair only from an authorized dealer
Related codes
Error U3520 by Vehicle Brand
FAQ
What does the U3520 code mean?
U3520 is an OBD-II diagnostic trouble code that indicates: High Voltage System Interlock Circuit E High
What causes a U3520 error code?
The most common causes of U3520 include: Open or short circuit in the interlock circuit; High Voltage Lockout Sensor Malfunction; Damage to the high voltage system wiring harness; Problems with the high voltage system control module.
How do I fix a U3520 diagnostic trouble code?
To fix U3520: Diagnose the high voltage interlock circuit. Check the integrity of the wiring harness and contacts. Test blocking sensors. For a complete diagnosis, use an OBD-II scanner.
Is it safe to drive with U3520?
Do not drive — repair immediately
How much does it cost to fix U3520?
The estimated repair cost for U3520 is $56–278. Actual cost depends on your vehicle, location, and labor rates.
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