P0674 Cylinder 4 Glow Plug Circuit

P0674 points to a cylinder 4 glow plug circuit problem. The controller detected an abnormal electrical response from the cylinder 4 glow plug path.

Code status

Needs verification

Not yet verified against SAE J2012_202509 / J2012DA. Treat unverified rows as a lookup aid, not repair authority.

System: Computer
Scope: iso-sae-controlled-p0
Standard: SAE J2012 / ISO 15031-6
Source: legacy-import

Diagnostic boundary

A diagnostic trouble code reports that a monitored test failed. It does not prove one specific part is bad, and manufacturer logic can add vehicle-specific conditions.

Do not replace the glow plug module until the cylinder 4 plug and branch wiring have been isolated.

Useful checks before replacing parts

Check cylinder 4 glow plug resistance, control module output, command voltage, current draw, battery voltage, and freeze-frame temperature conditions.
Inspect the cylinder 4 harness lead, connector corrosion, terminal tension, heat damage, module connector pins, and possible open or short faults.
Compare cylinder 4 current ramp and resistance with known good cylinders to confirm whether the fault follows the plug or the circuit.

Related OBD-II codes

These nearby computer entries can help compare wording and fault area. They may share the same verification status as the source database.