P0670 Glow Plug Module Control Circuit

P0670 indicates a glow plug module control circuit problem. The controller cannot command or monitor the diesel glow plug control module correctly.

Code details

Generic OBD-II · P0

System: Computer
Code type: Generic (SAE / ISO controlled)
Standard: SAE J2012 / ISO 15031-6

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 all glow plugs for P0670 until the shared control module power, ground, and command circuit are tested.

Symptoms of P0670

Check-engine light, sometimes with several unrelated codes at once.
Warning lights, a no-start, or intermittent electrical faults.
Communication or module-reset problems on a scan tool.

Common causes of P0670

Low battery voltage, poor grounds, corroded connectors, or blown fuses.
Wiring or network (CAN bus) faults between modules.
A module software/programming issue, or rarely a failed controller.

Useful checks before replacing parts

Check glow plug command, module power feed, relay status, battery voltage, coolant temperature, intake temperature, freeze-frame data, and related glow plug codes.
Inspect high-current power connections, fuses, fusible links, grounds, module connector heat damage, control wiring, and corrosion at glow plug terminals.
Command the glow system where supported and verify module output current and voltage before testing individual glow plugs.

Related OBD-II codes

These nearby computer entries can help compare wording and pin down the fault area.