OBD Guide
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B3840

Park Lamp Signal Circuit Low

B3840 is an OBD-II diagnostic trouble code meaning: Park Lamp Signal Circuit Low. Common causes: open or short circuit in wiring harness, faulty size relay. Estimated repair cost: $11–56.

Severity
⚠️ Medium
Can you drive?
Do not drive — repair immediately
Approx. repair cost
$11–56 (est.)

Symptoms

  • Side lights don't work
  • Side lights are flashing
  • Error on the dashboard

Causes

  • Open or short circuit in wiring harness
  • Faulty size relay
  • Blown fuse
  • Faulty side light bulbs
  • Problems with the ECU

How to Fix

  1. Check side light fuses
  2. Check lamps for burnout
  3. Inspect the wiring harness for damage
  4. Check side light relay
  5. If necessary, replace faulty components

Related codes

B3841B3842

Error B3840 by Vehicle Brand

AcuraAudiBAICBMWBYDBuickCadillacChanganCheryChevroletChryslerCitroenDodgeDongfengExeedFAWFordForthingFotonGACGMGMCGeelyGreat WallHavalHondaHongqiHyundaiInfinitiJACJaecooJaguarJeepJetourKaiyiKiaLadaLexusLi AutoLifanLincolnLivanMazdaMercedes-BenzMercuryMitsubishiNIONissanOldsmobileOmodaOpelPeugeotPlymouthPontiacRenaultSWMSaturnSkodaSkywellSubaruSuzukiTankToyotaVolkswagenVolvoVoyahXPengZeekrZotye

FAQ

What does the B3840 code mean?

B3840 is an OBD-II diagnostic trouble code that indicates: Park Lamp Signal Circuit Low

What causes a B3840 error code?

The most common causes of B3840 include: Open or short circuit in wiring harness; Faulty size relay; Blown fuse; Faulty side light bulbs.

How do I fix a B3840 diagnostic trouble code?

To fix B3840: Check side light fuses. Check lamps for burnout. Inspect the wiring harness for damage. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with B3840?

Do not drive — repair immediately

How much does it cost to fix B3840?

The estimated repair cost for B3840 is $11–56. Actual cost depends on your vehicle, location, and labor rates.

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See also: Russian version · NationStat