Is It Safe to Drive With a P0674 Code?
Common Symptoms of a P0674 Fault
Hard cold starting
White smoke at cold start
Rough cold idle
EML on
Possible Causes of P0674
A P0674 code can be triggered by faults across several systems. Identifying the exact root cause requires proper diagnostic equipment and live data — not just reading the code.
Glow Plug 4 Failure
Glow plug in cylinder 4 has failed.
Glow Plug 4 Wiring Fault
Wiring to cylinder 4 glow plug is damaged.
Connector Fault
Connector to cylinder 4 glow plug.
Control Module Output Fault
Glow plug controller output for cylinder 4.
Why we don't list the exact part: A P0674 code tells you what's happening but not why. Replacing parts without diagnosis is the most common way drivers waste money. A proper diagnosis identifies the specific cause first.
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P0674 and Your MOT
A stored P0674 fault code will cause your car to fail its MOT. The engine management light will be illuminated during the test — an automatic failure. Get the fault diagnosed and repaired, then have the code cleared before booking your test.