Fault code lookup

PowertrainP0684

Serious

Severity: Serious - have it checked soon

Glow Plug Control Module 1 to PCM Communication Circuit Range/Performance

30 brands affected · Generic SAE J2012 description.

Key terms: Control module: a small computer that runs one part of the car · SAE J2012: the standard generic code list · Powertrain: engine, transmission and emissions

1What it means in plain English

The engine computer or one of its output circuits has a fault.

2Common causes

  1. Engine control module fault
  2. Power or ground connection problem
  3. Low battery or charging voltage
  4. Wiring short or open circuit
  5. Software or memory fault

3Can I drive?

Serious · drive with care

If the engine runs normally, drive carefully to a workshop for diagnosis. If it runs badly, stalls, or will not restart, have the car towed.

This page gives general information. It is not professional advice. For a definite diagnosis and a repair quote, ask a qualified mechanic to inspect the car.

4Brand data 30

BrandCodeDescriptionSystem
Ashok Leyland CVP0684Glow Plug Control Module 1 to PCM Communication Circuit Range/Performance SAEPowertrain
BAIC MotorP0684Glow Plug Control Module to PCM Communication Circuit Range/Performance BrandPowertrain
BYDP0684Glow Plug Control Module to PCM Communication Circuit Range/Performance BrandPowertrain
CheryP0684HCU communication error BrandPowertrain
DaewooP0684Glow Plug Control Module to PCM Communication Circuit Range/Performance BrandPowertrain
DFFSP0684Glow Plug Control Module to PCM Communication Circuit Range/Performance BrandPowertrain
DFFXP0684Glow Plug Control Module to PCM Communication Circuit Range/Performance BrandPowertrain
DFXKP0684Glow Plug Control Module (J271): Implausible Signal BrandPowertrain
EOBDP0684Gløderørsstyremodul 1 til PCM-kommunikationskreds, område/ydelse BrandPowertrain
FordP0684Glow Plug Control Module 1 to PCM Communication Circuit Range/Performance SAEPowertrain
GeelyP0684Glow Plug Control Module (J271): Implausible Signal BrandPowertrain
GMP0684Glow Plug Control Module to PCM Communication Circuit Range/Performance BrandPowertrain
Great WallP0684Glow Plug Control Module to PCM Communication Circuit Range/Performance BrandPowertrain
HafeiP0684Glow Plug Control Module to PCM Communication Circuit Range/Performance BrandPowertrain
HoldenP0684Glow Plug Control Module Communication Circuit BrandPowertrain
HyundaiP0684Glow Plug Control Module 1 to PCM Communication Circuit Range/Performance SAEPowertrain
IsuzuP0684Glow Plug Control Module 1 to PCM Communication Circuit Range/Performance SAEPowertrain
Land RoverP0684Glow Plug Control Module 1 To PCM Communication Circuit Range/Performance BrandPowertrain
MazdaP0684Glow Plug Control Module 1 to PCM Communication Circuit Range/Performance SAEPowertrain
MitsubishiP0684Glow plug communication range BrandPowertrain
OpelP0684Glow Plug Control Module to PCM Communication Circuit Range/Performance BrandPowertrain
PeugeotP0684Glow Plug Control Module 1 to PCM Communication Circuit Range/Performance SAEPowertrain
PorscheP0684Glow Plug Control Module 1 to PCM Communication Circuit Range/Performance SAEPowertrain
ProtonP0684Glow plug communication range BrandPowertrain
SaabP0684Glow Plug Control Module to PCM Communication Circuit Range/Performance BrandPowertrain
MG (SAIC)P0684Glow Plug Control Module to PCM Communication Circuit Range/Performance BrandPowertrain
SuzukiP0684Glow Plug Control Module to PCM Communication Circuit Range / Performance BrandPowertrain
TataP0684PPH Relay Control - Relay = 0- Plugs = 1 BrandPowertrain
ToyotaP0684Glow Plug Control Module to PCM Communication Circuit Range/Performance BrandPowertrain
VolkswagenP0684Glow plug control module (J179): implausible signal BrandPowertrain

Legend: SAE is the generic J2012 description; Brand is text taken from that manufacturer’s data. Manufacturer rows keep the wording and language of the source data, and non-English text is tagged so screen readers pronounce it correctly.

5Extended variant codes 2

These 7-character codes are manufacturer-specific variants of P0684 and may be reported by some scan tools.

BrandCodeDescriptionSystem
HyundaiP068400If error feedback signal from the glow relay unit is detected, ECM sets DTC BrandPowertrain
SsangYongP068400Glow plug communication fault BrandPowertrain

6Related codes

  • P0680 Cylinder 10 Glow Plug Circuit/Open
  • P0681 Cylinder 11 Glow Plug Circuit/Open
  • P0682 Cylinder 12 Glow Plug Circuit/Open
  • P0683 Glow Plug Control Module 1 to PCM Communication Circuit
  • P0685 ECM/PCM Power Relay Control Circuit/Open
  • P0686 ECM/PCM Power Relay Control Circuit Low
  • P0687 ECM/PCM Power Relay Control Circuit High
  • P0688 ECM/PCM Power Relay Sense Circuit/Open
  • P0689 ECM/PCM Power Relay Sense Circuit Low
  • P068A ECM/PCM Power Relay De-Energized Performance - Too Early
  • P068B ECM/PCM Power Relay De-Energized Performance Too Late
  • P068C ECU internal fault (center 1st row pretensioner ignition system)

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