OBD Guide
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P05F9

Stop-Start Status Signal Circuit

P05F9 is an OBD-II diagnostic trouble code meaning: Stop-Start Status Signal Circuit. Common causes: open or short circuit in the start-stop status signal circuit, malfunction of the start-stop system control unit. Estimated repair cost: $22–167.

Severity
✅ Low
Can you drive?
Yes, but get it checked soon
Approx. repair cost
$22–167 (est.)

Symptoms

  • The start-stop system does not work (the engine does not turn off when stopping)
  • The indicator for disabling the start-stop system is on
  • Check Engine Light Is On
  • Other symptoms characteristic of a failure of the start-stop system

Causes

  • Open or short circuit in the start-stop status signal circuit
  • Malfunction of the start-stop system control unit
  • Battery malfunction (AGM battery with reduced capacity)
  • Problems with the CAN data bus
  • Malfunction of the sensor used by the start-stop system

How to Fix

  1. Read codes using a scanner, check for CAN bus codes
  2. Check the AGM battery (special battery tester - capacity, internal resistance)
  3. Inspect the connectors of the start-stop system control unit
  4. Check the wiring of the status signal circuit for open circuit and short circuit.
  5. Check the correct operation of the CAN bus between the blocks
  6. Diagnose the start-stop system control unit

Related codes

P05FAP05FBP0A7FP0AA6

Error P05F9 by Vehicle Brand

AcuraAudiBAICBMWBYDBuickCadillacChanganCheryChevroletChryslerCitroenDodgeDongfengExeedFAWFordForthingFotonGACGMGMCGeelyGreat WallHavalHondaHongqiHyundaiInfinitiJACJaecooJaguarJeepJetourKaiyiKiaLadaLexusLi AutoLifanLincolnLivanMazdaMercedes-BenzMercuryMitsubishiNIONissanOldsmobileOmodaOpelPeugeotPlymouthPontiacRenaultSWMSaturnSkodaSkywellSubaruSuzukiTankToyotaVolkswagenVolvoVoyahXPengZeekrZotye

FAQ

What does the P05F9 code mean?

P05F9 is an OBD-II diagnostic trouble code that indicates: Stop-Start Status Signal Circuit

What causes a P05F9 error code?

The most common causes of P05F9 include: Open or short circuit in the start-stop status signal circuit; Malfunction of the start-stop system control unit; Battery malfunction (AGM battery with reduced capacity); Problems with the CAN data bus.

How do I fix a P05F9 diagnostic trouble code?

To fix P05F9: Read codes using a scanner, check for CAN bus codes. Check the AGM battery (special battery tester - capacity, internal resistance). Inspect the connectors of the start-stop system control unit. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with P05F9?

Yes, but get it checked soon

How much does it cost to fix P05F9?

The estimated repair cost for P05F9 is $22–167. Actual cost depends on your vehicle, location, and labor rates.

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