P0677 Cylinder 7 Glow Plug Circuit

P0677 indicates a cylinder 7 glow plug circuit fault. The controller detected an electrical fault in the glow plug circuit for cylinder 7.

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 a bank of glow plugs until cylinder 7 has been compared against known good circuits.

Useful checks before replacing parts

Check cylinder 7 glow plug resistance, commanded voltage, current draw, battery condition, coolant temperature, and freeze-frame cold-start data.
Inspect cylinder 7 connector terminals, module output, harness heat damage, corrosion, rubbed wiring, and shorts to ground or power.
Compare cylinder 7 current draw against the other bank or neighboring cylinders to isolate the failed load or circuit branch.

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.