P0670 OBD-II Trouble Code: Glow Plug Module Control Circuit

Our certified mechanics come to you · 12-month, 12,000-mile warranty

SCHEDULE P0670 DIAGNOSTIC Get a fair and transparent estimate upfront
Red-stars EXCELLENT RATING ON

Cost of diagnosing the P0670 code

P0670 is a diagnostic trouble code (DTC) for "Glow Plug Module Control Circuit". This can happen for multiple reasons and a mechanic needs to diagnose the specific cause for this code to be triggered in your situation. Our certified mobile mechanics can come to your home or office to perform the Check Engine Light diagnostic for $70.00. Once we are able to diagnose the problem, you will be provided with an upfront quote for the recommended fix and receive $30.00 off as a credit towards the repair. All our repairs are backed by our 12-month / 12,000-mile warranty.

Cars Estimate Credit towards follow-up repair Earliest Availability
Ford$70.00$30.00
Toyota$70.00$30.00
BMW$70.00$30.00
SCHEDULE P0670 DIAGNOSTIC Get a fair and transparent estimate upfront

check engine light

P0670 code definition

If your vehicle’s ECM detects a problem with the Glow Plug Control Module (GPCM) control circuit, this code gets stored.

What the P0670 code means

Unlike gas engines, diesel engines don’t use sparkplugs for ignition. Instead, they rely on glow plugs for this important task. As the name would suggest, the Glow Plug Control Module is a big part of this. If it isn’t working correctly, your engine may not start.

What causes the P0670 code?

One problem could simply be the GPCM itself. A defective GPCM will set off this code all on its own. Other common issues that lead to a P0670 code are:

  • GPCM harness that’s shorted or open
  • GPCM circuit that’s suffering from a poor electrical connection
  • The ECM isn’t working correctly (this is pretty rare)

What are the symptoms of the P0670 code?

The most obvious problem related to this code is that your diesel engine simply won’t start. At the very least, it will most likely hesitate before coming to life. Usually, if the weather is warm, even a P0670 code shouldn’t stop your vehicle from starting. However, if it’s cold out, you’ll probably have a lot more trouble getting going.

Even if the engine does start, you will most likely hear a very loud knocking noise coming from it. This will continue until the engine warms and is able to function normally within an acceptable operating temperature.

White smoke may also come out of your vehicle’s exhaust. This is because the hard start produces excess fuel that must be burned off. The engine will have a noticeable miss before the cylinder head temperature increases enough to sustain total combustion.

How does a mechanic diagnose the P0670 code?

First, your mechanic will use their OBD-II scanner to diagnose which codes have been stored. Then, they’re going to check to see if your battery is working. Next, they’ll inspect the wiring, looking for any defects that may lead to the GPMC not getting the power it needs to work properly. A voltmeter helps with this.

After all that, they’re going to check to see if the ignition switch delivers power. They’ll do the same with the relay actuation by unplugging the oil temperature sensor and then hitting the ignition.

Common mistakes when diagnosing the P0670 code

The biggest mistake mechanics make when this code is present is going right to replacing the glow plug. As it’s the most obvious feature of the problem, many people assume it’s simply not working. Although a brand new glow plug may function better at first, if you don’t address the underlying problems, it will only be a matter of time before you need to see a mechanic again.

How serious is the P0670 code?

Your life won’t be in danger when the P0670 code is stored. Likewise, it’s not going to lead to any serious damage to your vehicle. However, until this problem is fixed, you are in for a terrible time with your ignition. So, in that regard, this is a very serious issue that should be addressed right away.

What repairs can fix the P0670 code?

Your mechanic may do any of the following:

Additional comments for consideration regarding the P0670 code

Just because your diesel engine needs a couple extra seconds to start in the cold doesn’t mean your GPMC or glow plug need to be replaced or repaired.

Need help with a P0670 code?

At YourMechanic, we have an army of certified mobile mechanics ready to rescue you from the P0670 code and all kinds of other problems that can impact your vehicle. All you have to do is fill out this online form and we’ll quickly reply with a quote before scheduling an appointment. You can also call 1-800-701-6230 to speak with a service advisor about a good time and date for repairs. Our mechanics will happily meet you at your home or workplace.

trouble codes
Check Engine Light
P0670

Fast and easy Check Engine Light is on Inspection service at your home or office.

SCHEDULE P0670 DIAGNOSTIC
Get a fair and transparent estimate upfront

Recent Check Engine Light is on Inspection reviews

Excellent Rating


YourMechanic Check Engine Light is on Inspection Service

Average Rating

4.5/5

Number of Reviews

4,026

Rating Summary
3,683
169
45
25
104
3,683
169
45
25
104
Christopher

Christopher

24 years of experience
220 reviews
Christopher
24 years of experience
Wonderful, and very knowledgeable.
2003 CHEVROLET AVALANCHE 1500 - CHECK ENGINE LIGHT IS ON - TAMPA, FLORIDA
Christopher

Christopher

13 years of experience
19 reviews
Christopher
13 years of experience
Chris was really friendly. Honest and very helpful explaining what was wrong with my car. I would definitely recommend him.
2003 INFINITI G35 - CHECK ENGINE LIGHT IS ON - CITRUS HEIGHTS, CALIFORNIA
Leslie

Leslie

22 years of experience
2 reviews
Leslie
22 years of experience
Insanely fast, professional, helpful beyond just the initial problem. Cannot say enough good things about this guy. A+
2005 LEXUS RX330 - CHECK ENGINE LIGHT IS ON - DICKINSON, TEXAS
Kevin

Kevin

21 years of experience
119 reviews
Kevin
21 years of experience
Did a great job and clearly explained what he had done.
2008 MERCEDES-BENZ GL450 - CHECK ENGINE LIGHT IS ON - SUWANEE, GEORGIA

More related articles

P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...
Insurance Requirements for Car Registration in Kentucky
The Kentucky Transportation Cabinet requires that all drivers in Kentucky carry liability automotive insurance, or “financial responsibility” in order to operate a vehicle legally and maintain vehicle...
P2159 OBD-II Trouble Code: Vehicle Speed Sensor B Range/Performance
Diagnostic Trouble Code (DTC): P2159 P2159 code definition Vehicle Speed Sensor B Range/Performance...

Related questions

Q: Fuel pump Check Engine Light issue with operational fuel pump

Code 47 (OBD-1) is the only code that pertains to "fuel pump related faults" in your car, so presumably that is the code that is recurring. If it is not Code 47, but rather a different code, that you are...

Q: The RPM is racing up and down when in park. Dashboard lights come on one at a time and then the car runs badly

Hi there. I understand your situation and concern. Fist we need the codes that are stored when the Check Engine Light comes on. Any diagnostic scan tool should be able to give us the codes that are set and give...

Q: Check Engine Light P0420 trouble code

Hi there, thanks for writing in. Typically, a P0420 code (catalyst efficiency insufficient) is the catalytic converter not properly functioning. Chances are, the Check Engine Light going off and then back on, it's still the P0420 code that is present....

How can we help?

Our service team is available 7 days a week, Monday - Friday from 6 AM to 5 PM PST, Saturday - Sunday 7 AM - 4 PM PST.

1-800-701-6230 · hi@yourmechanic.com