OBD Guide
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U3543

High Voltage System Interlock Circuit O Low

U3543 is an OBD-II diagnostic trouble code meaning: High Voltage System Interlock Circuit O Low. Common causes: open circuit in high voltage blocking circuit, damaged or oxidized connector contacts. Estimated repair cost: $56–167.

Severity
🔴 High
Can you drive?
Do not drive — repair immediately
Approx. repair cost
$56–167 (est.)

Symptoms

  • Check Engine light comes on
  • Possible problems starting the electric vehicle
  • The system may limit engine power
  • A warning message appears on the dashboard

Causes

  • Open circuit in high voltage blocking circuit
  • Damaged or oxidized connector contacts
  • Lock sensor malfunction
  • Problems with the high voltage system wiring harness
  • Malfunction of the high-voltage system control unit

How to Fix

  1. Check the integrity of the high voltage blocking circuit
  2. Inspect and clean the connector contacts
  3. Check the condition of the high voltage system wiring harness
  4. Test high voltage block sensor
  5. If necessary, replace damaged components
  6. Repair only from an authorized dealer

Related codes

U3541U3542U3544

Error U3543 by Vehicle Brand

AcuraAudiBAICBMWBYDBuickCadillacChanganCheryChevroletChryslerCitroenDodgeDongfengExeedFAWFordForthingFotonGACGMGMCGeelyGreat WallHavalHondaHongqiHyundaiInfinitiJACJaecooJaguarJeepJetourKaiyiKiaLadaLexusLi AutoLifanLincolnLivanMazdaMercedes-BenzMercuryMitsubishiNIONissanOldsmobileOmodaOpelPeugeotPlymouthPontiacRenaultSWMSaturnSkodaSkywellSubaruSuzukiTankToyotaVolkswagenVolvoVoyahXPengZeekrZotye

FAQ

What does the U3543 code mean?

U3543 is an OBD-II diagnostic trouble code that indicates: High Voltage System Interlock Circuit O Low

What causes a U3543 error code?

The most common causes of U3543 include: Open circuit in high voltage blocking circuit; Damaged or oxidized connector contacts; Lock sensor malfunction; Problems with the high voltage system wiring harness.

How do I fix a U3543 diagnostic trouble code?

To fix U3543: Check the integrity of the high voltage blocking circuit. Inspect and clean the connector contacts. Check the condition of the high voltage system wiring harness. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with U3543?

Do not drive — repair immediately

How much does it cost to fix U3543?

The estimated repair cost for U3543 is $56–167. Actual cost depends on your vehicle, location, and labor rates.

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See also: Russian version · NationStat