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. Once we are able to diagnose the problem, you will be provided with an upfront quote for the recommended fix and receive $20.00 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$20.00
Toyota$20.00
BMW$20.00
SCHEDULE P0670 DIAGNOSTIC Get a fair and transparent estimate upfront

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 1-800-701-6220 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
P0670
Check Engine Light

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

4.8/5

Number of Reviews

4,810

Rating Summary
4,424
187
47
28
124
4,424
187
47
28
124

Joel

19 years of experience
741 reviews
Joel
19 years of experience
Acura RL - Check Engine Light is on - Jacksonville, Florida
very knowledgeable and precise. able to fix electrical issues in my car. Right on time for the appointment.

Christopher

15 years of experience
41 reviews
Christopher
15 years of experience
Honda Accord - Check Engine Light is on - Fairburn, Georgia
Christopher was excellent! He explained everything in detail to make sure I understood. He was professional and provided me with the next course of actions to resolve my care issues. I'm glad he was sent to service my car.

Alexander

18 years of experience
58 reviews
Alexander
18 years of experience
Saab 9-7x - Check Engine Light is on - Kissimmee, Florida
He was very friendly and very helpful . I felt like it was being around a close friend , also gave me so very good advice on my car & future advice about it . Highly recommend mechanic, would use his services again .

Matthew

31 years of experience
639 reviews
Matthew
31 years of experience
Jeep Patriot - Check Engine Light is on - Norfolk, Virginia
Matthew was on time which was a relief, he is very knowledgeable and was easy to understand what was wrong and what was being done. I am recommending to friends and family due to the great experience Matthew gave me. Extremely professional 10/10

More related articles

P2423 OBD-II Trouble Code: HC Adsorption Catalyst Efficiency Below Threshold Bank 1
P2423 P2423 Code Definition A P2423 code is a generic powertrain code related to emissions systems problems. In this case, the hydrocarbon adsorption and catalyst efficiency is below the allowed threshold in engine bank 1 (typically the number 1 cylinder)....
Tips for Taking Care of Your Exhaust System
Your Your car’s exhaust system might not be the first thing you think about when it comes to engine performance or personal safety, but it should be pretty high on that list. Your engine combusts fuel and air in order...
P2161 OBD-II Trouble Code: Vehicle Speed Sensor B Intermittent/Erratic
P2161 P2161 trouble code definition Vehicle Speed Sensor B Intermittent/Erratic What the P2161 code means P2161 is an OBD-II generic code for the engine control module (ECM) detecting the vehicle speed sensor 2 or B giving an intermittent or erratic...

Related questions

Hi, my engine light has started to flash and my car is shuddering and getting worse - especially when stationary. The engine light

Hello, thank you for writing in. The symptoms you are having can come from a range of different issues with the vehicle. There may be a sensor that is failing, low fuel pressure, a spark and ignition issue, or an...

Check engine light and temporary loss of steering/accelerator

Hello. The symptoms you describe can be caused by different things. Both the throttle and steering on your vehicle are electronically controlled, and can have problems if any of the components to these systems have issues. If the throttle body...

The check engine light is on, the car feels as if it will turn off while idling, gas smell

Hi there. A gas smell such as this is a good indication that there is a fuel leak. If it is entering the vehicle, then it is typically under the hood. Most of the time on this vehicle it comes...

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