Code Definition

P0674 — Cylinder 4 Glow Plug Circuit/Open

System: Powertrain  |  Type: Generic (OBD-II Standard)  |  Make: Generic

About P0674

P0674 is a generic (obd-ii standard) powertrain diagnostic trouble code. It belongs to the P-prefix family of codes, which covers engine, transmission, emissions, or fuel-system faults.

When P0674 is stored, the module has detected an open (broken or disconnected) electrical path in the monitored circuit; and a signal or supply voltage lower than the expected operating range.

Scanning & clearing: A generic OBD-II scan tool will usually read and clear powertrain (P) codes. For live data, freeze-frame capture, and bi-directional tests you may need a more capable scan tool that supports the vehicle's ECM protocol.

Because P0674 is a generic OBD-II code, its base definition is shared across manufacturers. The specific diagnostic steps, reference values, and repair procedures can vary by vehicle, and the TaT Diagnostic Assistant includes verified procedures submitted by working technicians.

Code Information

The P0674 code is set when the glow plug control module or Engine Control Module (ECM) detects an open circuit in the Cylinder 4 glow plug circuit. In a diesel engine the glow plugs are heating elements that warm the combustion chambers to help the engine start and run cleanly when cold. An open in the Cylinder 4 circuit means the electrical path to that glow plug is broken, so it does not heat. This most often comes from a failed glow plug element or a poor connection at that cylinder. Symptoms can include harder or longer cold starting, rough running and white smoke shortly after a cold star...

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