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StartingSeverity Medium: diagnose soon

P0671Cylinder 1 Glow Plug Circuit

What it means

The glow plug control sees an electrical fault in the cylinder 1 glow plug circuit, usually an open plug. With the engine warm the car runs normally, so the code and a measurement are the only clues.

Symptoms

  • Hard cold start
  • White smoke and shaking for a few seconds after a cold start
  • Glow plug warning light on some cars

Common causes

  • Open glow plug on cylinder 1
  • Broken or corroded glow plug wire or connector
  • Glow plug control module fault

What to check first

  1. Measure the glow plug resistance (typically 0.5–1.5 Ω; OL means open)
  2. Check the supply from the control module during pre-glow
  3. If one plug failed, check the others: they are usually the same age
Can I drive with P0671? Usually yes for a short distance, but performance or economy may suffer and the fault can get worse. Diagnose it soon.
Practise it: Glow plug, cyl. 1 (diesel) in the engine simulator shows this fault in live data, tests and on the scope.Open in the simulator

Generic OBD-II meaning. Manufacturer-specific meanings and checks can differ; always check the service information for the car.

How to test the parts behind P0671

Diesel glow plugsWiring, typical values, multimeter and scope tests

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P0671: questions and answers

What does P0671 mean?

P0671: Cylinder 1 Glow Plug Circuit. The glow plug control sees an electrical fault in the cylinder 1 glow plug circuit, usually an open plug. With the engine warm the car runs normally, so the code and a measurement are the only clues.

What are the symptoms of P0671?

Hard cold start. White smoke and shaking for a few seconds after a cold start. Glow plug warning light on some cars.

What causes P0671?

Open glow plug on cylinder 1. Broken or corroded glow plug wire or connector. Glow plug control module fault.

How do you diagnose P0671?

1. Measure the glow plug resistance (typically 0.5–1.5 Ω; OL means open) 2. Check the supply from the control module during pre-glow 3. If one plug failed, check the others: they are usually the same age

Can I drive with P0671?

Usually yes for a short distance, but performance or economy may suffer and the fault can get worse. Diagnose it soon.