OBD Guide
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U0120

Lost Communication With Starter / Generator Control Module

U0120 is an OBD-II diagnostic trouble code meaning: Lost Communication With Starter / Generator Control Module. Common causes: open or short circuit in the communication circuit, starter/generator control module malfunction. Estimated repair cost: $56–278.

Severity
🔴 High
Can you drive?
Limited driving only, diagnose soon
Approx. repair cost
$56–278 (est.)

Symptoms

  • Problems starting the engine
  • Check Engine Light Is On
  • Disabling the start-stop system
  • Low battery
  • Other related errors appear

Causes

  • Open or short circuit in the communication circuit
  • Starter/Generator Control Module Malfunction
  • Module power problems
  • Wiring harness damage
  • Software errors in the ECU

How to Fix

  1. Check the integrity of the wiring harness and connectors
  2. Check fuses and relays associated with the module
  3. Diagnose the starter/generator control module
  4. Update ECU software if necessary
  5. Replace the faulty module if the breakdown is confirmed

Related codes

U0121U0122U0123

Error U0120 by Vehicle Brand

AcuraAudiBAICBMWBYDBuickCadillacChanganCheryChevroletChryslerCitroenDodgeDongfengExeedFAWFordForthingFotonGACGMGMCGeelyGreat WallHavalHondaHongqiHyundaiInfinitiJACJaecooJaguarJeepJetourKaiyiKiaLadaLexusLi AutoLifanLincolnLivanMazdaMercedes-BenzMercuryMitsubishiNIONissanOldsmobileOmodaOpelPeugeotPlymouthPontiacRenaultSWMSaturnSkodaSkywellSubaruSuzukiTankToyotaVolkswagenVolvoVoyahXPengZeekrZotye

FAQ

What does the U0120 code mean?

U0120 is an OBD-II diagnostic trouble code that indicates: Lost Communication With Starter / Generator Control Module

What causes a U0120 error code?

The most common causes of U0120 include: Open or short circuit in the communication circuit; Starter/Generator Control Module Malfunction; Module power problems; Wiring harness damage.

How do I fix a U0120 diagnostic trouble code?

To fix U0120: Check the integrity of the wiring harness and connectors. Check fuses and relays associated with the module. Diagnose the starter/generator control module. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with U0120?

Limited driving only, diagnose soon

How much does it cost to fix U0120?

The estimated repair cost for U0120 is $56–278. Actual cost depends on your vehicle, location, and labor rates.

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See also: Russian version · NationStat