P0670Generic code

P0670 Code: Glow Plug Module Control Circuit

The P0670 code means there is a fault in the circuit of the module that controls the glow plugs on a diesel engine. The engine will start poorly when cold. Check the glow plugs too, because a shorted plug can damage the module.

Severity
Low
Can I keep driving?
Yes, no immediate risk
Estimated cost
$50 to $600
Difficulty
Medium
System
Ignition and Misfires
Applies to
All OBD2 vehicles

Updated Reviewed by Renzo Chacca

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What the P0670 code means

The glow plug module takes its orders from the computer and powers the glow plugs. The P0670 code indicates a fault in its circuit: the power supply, the ground or the control signal.

Check the glow plugs as well. A shorted plug can damage the module.

On many modern diesels the glow plug module also controls the afterglow (plugs kept on after the engine starts) and reports the state of each plug to the computer. So when the module fails, codes often appear for individual plugs that are actually fine. Always test the plugs with a multimeter before you replace any of them.

P0670 code symptoms

  • Hard starting when cold.
  • White smoke.
  • Glow plug light on.

Likely causes of the P0670 code

  1. Glow plug module with damaged internal electronics.
  2. Blown high current fuse, often because of a shorted glow plug.
  3. Control wiring between the computer and the module or the relay.
  4. Shorted glow plug. It can damage the module output.

How to diagnose the P0670 code step by step

  1. Check the module power and ground.
  2. Measure the resistance of all the glow plugs.
  3. Check the control signal.
  4. Test each glow plug with a multimeter before replacing it. A module fault can point to plugs that are good.

How to fix the P0670 code

  • Replace the module or repair the wiring.
  • Replace shorted glow plugs.

Technical reference data

  • Module with a high current output for each glow plug.
  • Reference values: check the manufacturer data for your vehicle.

Brand-specific notes

This code is frequent on several popular diesels, and a shorted glow plug is worth ruling out on all of them.

P0670 on Ford Power Stroke

Frequent on the Ford Power Stroke.

P0670 on Volkswagen TDI

Frequent on the Volkswagen TDI.

P0670 on Chevrolet Duramax

Frequent on the Chevrolet Duramax.

Frequently asked questions about P0670

Can I drive with a P0670 code?
Yes. The engine runs once it is started, but it will be hard to start when cold, so get it repaired before winter.
Why does the module fail?
Sometimes because of a shorted glow plug, which overloads the module output. That is why you should test the plugs whenever the module is suspect.
What happens in winter?
The engine may not start at all in cold weather, because the glow plugs are what warm the cylinders for starting.
How much does it cost to fix P0670?
Between $50 and $600, depending on whether it is wiring, the module or shorted glow plugs.
What does the P0670 code mean?
It is a generic OBD2 code that means the circuit of the glow plug control module has a fault in its power, ground or control signal.
What is the most common cause of P0670?
A damaged module or a blown fuse caused by a shorted glow plug. Test the plugs first when you see a P0670 code.

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