OBD Guide
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P05F5

Exhaust Aftertreatment Power Relay Control Circuit High

P05F5 is an OBD-II diagnostic trouble code meaning: Exhaust Aftertreatment Power Relay Control Circuit High. Common causes: short circuit of the relay control circuit to the power line (+12v), damage to the insulation of the control wire (touching the positive bus). 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
  • Unstable or completely inoperative exhaust aftertreatment system
  • Possible relay overheating
  • Increased NOx or soot emissions
  • Other SCR/DPF system codes

Causes

  • Short circuit of the relay control circuit to the power line (+12V)
  • Damage to the insulation of the control wire (touching the positive bus)
  • Malfunction of the relay itself (internal breakdown of insulation to power supply)
  • ECU output transistor malfunction (high output voltage)
  • Incorrect connection diagram (repair error)

How to Fix

  1. Read codes, fix parameters
  2. Disconnect the relay connector, measure the voltage at the control contact with the ignition on
  3. If >1V when the ECU is turned off, there is a short circuit in the wiring
  4. Check the control wire from the relay to the computer for short circuit to the positive bus
  5. Inspect the wiring harness near hot surfaces and positive connections
  6. Replace the relay or eliminate the short circuit

Related codes

P05F3P05F4P05F6P05F7P20E8

Error P05F5 by Vehicle Brand

AcuraAudiBAICBMWBYDBuickCadillacChanganCheryChevroletChryslerCitroenDodgeDongfengExeedFAWFordForthingFotonGACGMGMCGeelyGreat WallHavalHondaHongqiHyundaiInfinitiJACJaecooJaguarJeepJetourKaiyiKiaLadaLexusLi AutoLifanLincolnLivanMazdaMercedes-BenzMercuryMitsubishiNIONissanOldsmobileOmodaOpelPeugeotPlymouthPontiacRenaultSWMSaturnSkodaSkywellSubaruSuzukiTankToyotaVolkswagenVolvoVoyahXPengZeekrZotye

FAQ

What does the P05F5 code mean?

P05F5 is an OBD-II diagnostic trouble code that indicates: Exhaust Aftertreatment Power Relay Control Circuit High

What causes a P05F5 error code?

The most common causes of P05F5 include: Short circuit of the relay control circuit to the power line (+12V); Damage to the insulation of the control wire (touching the positive bus); Malfunction of the relay itself (internal breakdown of insulation to power supply); ECU output transistor malfunction (high output voltage).

How do I fix a P05F5 diagnostic trouble code?

To fix P05F5: Read codes, fix parameters. Disconnect the relay connector, measure the voltage at the control contact with the ignition on. If >1V when the ECU is turned off, there is a short circuit in the wiring. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with P05F5?

Limited driving only, diagnose soon

How much does it cost to fix P05F5?

The estimated repair cost for P05F5 is $22–222. Actual cost depends on your vehicle, location, and labor rates.

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See also: Russian version · NationStat