OBD Guide
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P066D

Cylinder 2 Glow Plug Control Circuit High

P066D is an OBD-II diagnostic trouble code meaning: Cylinder 2 Glow Plug Control Circuit High. Common causes: short circuit of the glow plug control wire of cylinder 2 to power, open circuit in the spark plug control circuit. Estimated repair cost: $17–278.

Severity
⚠️ Medium
Can you drive?
Yes, but get it checked soon
Approx. repair cost
$17–278 (est.)

Symptoms

  • Difficulty starting a diesel engine in cold weather
  • The Check Engine light comes on
  • Extended warm-up time before starting
  • White or gray smoke from exhaust pipe when starting
  • Unstable idle after cold start

Causes

  • Short circuit of the glow plug control wire of cylinder 2 to power
  • Open circuit in the spark plug control circuit
  • Glow Plug Control Module (GPCM) Malfunction
  • Damage to wiring or connectors
  • Internal ECU fault

How to Fix

  1. Read error codes with an OBD-II scanner, capture a freeze frame
  2. Inspect the wiring and connectors of the cylinder 2 glow plug and GPCM
  3. Measure the voltage in the glow plug control circuit of cylinder 2
  4. Check the ground circuit for open circuit
  5. Check signal wire for short circuit to power
  6. If the external circuit is in good condition - diagnostics and replacement of the GPCM or ECU

Related codes

P066CP0672P066AP066BP0670

Error P066D by Vehicle Brand

AcuraAudiBAICBMWBYDBuickCadillacChanganCheryChevroletChryslerCitroenDodgeDongfengExeedFAWFordForthingFotonGACGMGMCGeelyGreat WallHavalHondaHongqiHyundaiInfinitiJACJaecooJaguarJeepJetourKaiyiKiaLadaLexusLi AutoLifanLincolnLivanMazdaMercedes-BenzMercuryMitsubishiNIONissanOldsmobileOmodaOpelPeugeotPlymouthPontiacRenaultSWMSaturnSkodaSkywellSubaruSuzukiTankToyotaVolkswagenVolvoVoyahXPengZeekrZotye

FAQ

What does the P066D code mean?

P066D is an OBD-II diagnostic trouble code that indicates: Cylinder 2 Glow Plug Control Circuit High

What causes a P066D error code?

The most common causes of P066D include: Short circuit of the glow plug control wire of cylinder 2 to power; Open circuit in the spark plug control circuit; Glow Plug Control Module (GPCM) Malfunction; Damage to wiring or connectors.

How do I fix a P066D diagnostic trouble code?

To fix P066D: Read error codes with an OBD-II scanner, capture a freeze frame. Inspect the wiring and connectors of the cylinder 2 glow plug and GPCM. Measure the voltage in the glow plug control circuit of cylinder 2. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with P066D?

Yes, but get it checked soon

How much does it cost to fix P066D?

The estimated repair cost for P066D is $17–278. Actual cost depends on your vehicle, location, and labor rates.

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