OBD Guide
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P05F4

Exhaust Aftertreatment Power Relay Control Circuit Low

P05F4 is an OBD-II diagnostic trouble code meaning: Exhaust Aftertreatment Power Relay Control Circuit Low. Common causes: relay control circuit short to ground, damage to control wire insulation. Estimated repair cost: $22–222.

Severity
🔴 High
Can you drive?
Limited driving only, diagnose soon
Approx. repair cost
$22–222 (est.)

Symptoms

  • Check Engine Light and Emission System Warning Light Illuminates
  • Incorrect operation or complete failure of SCR/DPF
  • Increased emissions
  • Possible power limitation
  • Unstable operation of the neutralization system relay

Causes

  • Relay control circuit short to ground
  • Damage to control wire insulation
  • Internal defect of the relay control winding (short circuit of turns)
  • Moisture getting into the relay connector
  • ECU output stage malfunction

How to Fix

  1. Read codes, check for related codes
  2. Disconnect the control connector of the relay, measure the voltage on the control wire
  3. Check the resistance of the control circuit to ground (with the computer turned off)
  4. Inspect the wiring for pinches on metal parts
  5. Check the connector for signs of moisture or corrosion.
  6. Replace the relay or eliminate the short circuit in the control circuit

Related codes

P05F3P05F5P05F6P05F7P20E8

Error P05F4 by Vehicle Brand

AcuraAudiBAICBMWBYDBuickCadillacChanganCheryChevroletChryslerCitroenDodgeDongfengExeedFAWFordForthingFotonGACGMGMCGeelyGreat WallHavalHondaHongqiHyundaiInfinitiJACJaecooJaguarJeepJetourKaiyiKiaLadaLexusLi AutoLifanLincolnLivanMazdaMercedes-BenzMercuryMitsubishiNIONissanOldsmobileOmodaOpelPeugeotPlymouthPontiacRenaultSWMSaturnSkodaSkywellSubaruSuzukiTankToyotaVolkswagenVolvoVoyahXPengZeekrZotye

FAQ

What does the P05F4 code mean?

P05F4 is an OBD-II diagnostic trouble code that indicates: Exhaust Aftertreatment Power Relay Control Circuit Low

What causes a P05F4 error code?

The most common causes of P05F4 include: Relay control circuit short to ground; Damage to control wire insulation; Internal defect of the relay control winding (short circuit of turns); Moisture getting into the relay connector.

How do I fix a P05F4 diagnostic trouble code?

To fix P05F4: Read codes, check for related codes. Disconnect the control connector of the relay, measure the voltage on the control wire. Check the resistance of the control circuit to ground (with the computer turned off). For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with P05F4?

Limited driving only, diagnose soon

How much does it cost to fix P05F4?

The estimated repair cost for P05F4 is $22–222. Actual cost depends on your vehicle, location, and labor rates.

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See also: Russian version · NationStat