OBD Guide
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P066C

Cylinder 2 Glow Plug Control Circuit Low

P066C is an OBD-II diagnostic trouble code meaning: Cylinder 2 Glow Plug Control Circuit Low. Common causes: short circuit of the glow plug control wire of cylinder 2 to ground, damaged or broken wiring in the 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
  • Increased starter cranking time
  • White smoke from the exhaust pipe during cold start
  • Unstable engine operation after starting

Causes

  • Short circuit of the glow plug control wire of cylinder 2 to ground
  • Damaged or broken wiring in the control circuit
  • Glow Plug Control Module (GPCM) Malfunction
  • Faulty glow plug cylinder 2 (internal short circuit)
  • Oxidation or damage to control circuit connectors

How to Fix

  1. Read error codes with an OBD-II scanner, write down all active codes
  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 resistance of the glow plug of cylinder 2 (normal: 0.5–2 Ohm)
  5. Check the circuit for short circuit to ground
  6. If the wiring is working properly - diagnostics and replacement of the GPCM or spark plug

Related codes

P066DP0672P066AP066BP0670

Error P066C by Vehicle Brand

AcuraAudiBAICBMWBYDBuickCadillacChanganCheryChevroletChryslerCitroenDodgeDongfengExeedFAWFordForthingFotonGACGMGMCGeelyGreat WallHavalHondaHongqiHyundaiInfinitiJACJaecooJaguarJeepJetourKaiyiKiaLadaLexusLi AutoLifanLincolnLivanMazdaMercedes-BenzMercuryMitsubishiNIONissanOldsmobileOmodaOpelPeugeotPlymouthPontiacRenaultSWMSaturnSkodaSkywellSubaruSuzukiTankToyotaVolkswagenVolvoVoyahXPengZeekrZotye

FAQ

What does the P066C code mean?

P066C is an OBD-II diagnostic trouble code that indicates: Cylinder 2 Glow Plug Control Circuit Low

What causes a P066C error code?

The most common causes of P066C include: Short circuit of the glow plug control wire of cylinder 2 to ground; Damaged or broken wiring in the control circuit; Glow Plug Control Module (GPCM) Malfunction; Faulty glow plug cylinder 2 (internal short circuit).

How do I fix a P066C diagnostic trouble code?

To fix P066C: Read error codes with an OBD-II scanner, write down all active codes. 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 P066C?

Yes, but get it checked soon

How much does it cost to fix P066C?

The estimated repair cost for P066C is $17–278. Actual cost depends on your vehicle, location, and labor rates.

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