P0674 code — how to fix error fast
Equip yourself with the knowledge of the P0674 code for a prime driving experience.
If you are driving a diesel-powered car and the code P0674 shows up, we know how you must feel. With all the problems that could emerge with emissions, the last thing you want to deal with are engine troubles, and that’s exactly what this code may bring.
Of course, you need professional insight into the situation and that’s where our experts will step in to help. We’ll bring you everything you need to know on dealing with the code – from finding the reason why it got active, to ways of making sure it’s not something else that’s behind the code. We’ll also discuss the possible solutions and ways of prevention to give you a full overview of the P0647 code meaning.
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What does the P0674 code mean?
The P0674 code is part of the OBD-II (On-Board Diagnostics) system, which monitors various systems in your car to ensure they are functioning correctly. When the glow plug control circuit has a problem, the P0674 code will appear on your dashboard. This code can indicate a problem with the glow plug itself, the control module, or the wiring that connects them.
Understanding the P0674 code is essential because it can help you identify potential problems before they become major issues. Ignoring this code can cause further damage to your car and lead to expensive repairs, so let’s move on right away with the possible reasons behind it.
What causes the P0674 code?
Several potential causes can trigger the P0674 code and that makes it hard to fix the issue at hand if you don’t know how to properly diagnose it. It’s useful to know about all the possible reasons, so here’s a list of the most common culprits behind the code:
Faulty glow plug
A faulty glow plug can cause the P0674 code to appear. Glow plugs are responsible for heating the engine’s cylinders to ensure they start correctly. If a glow plug is faulty, it can cause the engine to misfire, leading to the code’s appearance.
Faulty glow plug control module
The glow plug control module is responsible for controlling the glow plugs’ operation. If the control module is faulty, it can cause the P0674 code to appear.
Wiring issues
Wiring issues can also cause the P0674 code to appear. If the wiring that connects the glow plug and the control module is damaged, it can cause a short circuit, leading to the code’s appearance.
Which car models does the P0674 code affect the most?
It’s an understatement to say that this code is too general to give you a definitive list of the most commonly affected cars. The reason for that is, well, that simply all diesel engines can be equally affected, but there are rumors of some cars being more prone to the code. We dug up some of the NHTSA’s reports and driver complaints to back up that statement and here’s what we found:
- Chevy Silverado: Chevrolet Silverado diesel engines use glow plugs to start in cold weather conditions. The wiring harness for these glow plugs can become chafed by the engine block, leading to an open circuit and the P0674 code.
- GMC Sierra: The GMC Sierra diesel engines use a similar glow plug system as the Chevrolet Silverado. The wiring harness for these glow plugs can also become damaged by the engine block, leading to the P0674 code.
- Volkswagen Golf TDI: The Volkswagen Golf TDI is a diesel-powered vehicle that relies on the proper functioning of its four glow plugs to start. A faulty relay or control module can cause one or more of these glow plugs to malfunction and trigger the P0674 code.
- Mercedes-Benz Sprinter: The Mercedes-Benz Sprinter is a popular commercial van that uses diesel engines equipped with glow plugs. Like other diesel engines, faulty glow plugs or modules can cause this code to appear.
How to diagnose the P0674 code
Diagnosing the P0674 code requires a few steps and even if you know about the most likely reasons behind it, it takes testing for each of these to be sure that you’ve got it right. So, here’s what you can do to break the ice and pinpoint the exact issue that caused this code:
Use an OBD-II scanner
The first thing you need to do is use an OBD-II scanner to read the code. This scanner can provide you with information about the code and what might be causing it.
Inspect the glow plugs
After reading the code, inspect the glow plugs to see if any of them are faulty. You can use a multimeter to check the resistance of each plug. A faulty plug will have a higher resistance than the others.
Check the glow plug control module
If the glow plugs are functioning correctly, check the glow plug control module. Use a multimeter to check the voltage at the control module. If the voltage is incorrect, the control module may be faulty.
Check the wiring
If the control module is functioning correctly, check the wiring that connects the glow plugs and the control module. Look for any signs of damage or corrosion.
How to fix the P0674 code
Fixing the P0674 code depends on the underlying cause. While it’s mostly caused by glow spark issues, it’s handy to know about all the possible solutions:
Replace faulty glow plugs
If a faulty glow plug is causing the code, replace it with a new one. This fix is relatively simple and inexpensive and could range around $50 to $100 per plug. It’s best to replace all glow plugs when a single one fails since the replacement doesn’t work like replacing spark plugs on petrol-powered cars.
Replace the faulty glow plug control module
If the control module is faulty, replace it with a new one. This fix can be more expensive, but it’s still relatively simple and there’s no point in replacing glow plugs if the control module is faulty. They would still end up being unusable and you may not be able to start your car even with a new plug set.
Repair or replace wiring
If the wiring is damaged, repair or replace it. This fix is more complicated and may require professional help, but it shouldn’t cost more than $200 as it depends on the car model.
How to prevent the P0674 code
Preventing the P0674 code from appearing requires routine maintenance of your car’s glow plug system. Here are some preventative measures:
- Replace glow plugs regularly (as recommended by the manufacturer)
- Clean and inspect the glow plug system regularly
- Have a professional mechanic inspect the glow plug system during routine maintenance
By following these preventative measures, you can reduce the risk of the P0674 code appearing and ensure your car stays in optimal condition.
Our take
The P0674 code can be a cause for concern, but with the right knowledge and tools, you can diagnose and fix it. We may not be able to provide you with the tools, but we hope that we at least managed to educate you on the code and problems with the glow plugs and vehicle starting in general.
Now you should be equipped to tackle the issue and properly fix the situation without leaving any room for the code to come back.
What are the symptoms of the P0674 code?
The most common symptom of the P0674 code is difficulty starting the engine, particularly in cold weather conditions. Other symptoms may include rough idling, reduced power output, and increased emissions.
Can I still drive my vehicle with the P0674 code?
While it may be possible to drive your vehicle with the P0674 code, it’s not recommended. This code can cause starting issues and other problems that may make your vehicle unreliable or even dangerous to drive.
How can I prevent the P0674 code from occurring?
While there may not be a surefire way to prevent the P0674 code from occurring, there are some steps you can take to minimize your risk. This includes regular maintenance of your vehicle’s glow plugs and electrical system, avoiding exposure to extreme temperatures, and using high-quality fuel and additives.
