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Vehicle engine and/or automatic transmission

Code: P0672 - The electrical circuit for the glow plug in cylinder 2 (which helps start the engine in cold conditions) is open or not working.

P0672 is a diagnostic trouble code that points to a problem with the glow plug circuit for cylinder number two. In plain terms, your vehicle’s computer (the PCM) has noticed something isn’t right with how the glow plug for cylinder #2 is working. Glow plugs are found in diesel engines and their main job is to preheat the combustion chamber before you start the engine, especially when it’s cold out. Without them working properly, your diesel can be hard to start or might not start at all in chilly weather. This code is specifically about the electrical circuit for the glow plug in cylinder #2, so it’s not a general engine issue-it’s focused on that one spot.

Causes of P0672 engine code

From experience and what I see in the service manuals, most of the time, this code pops up because the glow plug itself in cylinder #2 has failed. But it’s not always that simple. Here’s what I usually find as the main culprits:

Faulty glow plug in cylinder #2 (burned out or open circuit)
Wiring issues-damaged, corroded, or loose wires or connectors in the glow plug circuit
Bad connection at the glow plug or control module
Faulty glow plug control module (the part that sends power to the plugs)

It’s best to start with the basics before jumping to conclusions about expensive parts.

Symptoms associated with P0672 code

When this code is active, you’ll probably notice a few things. First, the check engine light will be on. That’s your car’s way of saying something’s up. Most often, you’ll have trouble starting the engine, especially when it’s cold outside. Sometimes, it might not start at all. If it does start, you might feel the engine running rough or lacking power until it warms up. These symptoms are usually worse in cold weather, since that’s when the glow plugs are most needed.

Diagnosis steps for P0672

Here’s how I approach diagnosing a P0672 code, step by step. I always recommend starting simple and working your way up:

First, I clear the code and see if it comes back. Sometimes, it’s a fluke, but if it returns, it’s time to dig in.
I visually inspect the wiring and connectors going to the glow plug on cylinder #2. Look for any signs of damage, corrosion, or loose connections. Don’t forget to check the harness near the plug-sometimes wires get brittle or break right at the connector.
Next, I test the glow plug itself. With the engine off and the key out, I disconnect the glow plug and use a multimeter to check its resistance. Most good glow plugs read between 0.5 and 2 ohms. If it’s way higher or shows ‘open,’ it’s likely burned out and needs replacing.
If the glow plug checks out, I move on to the control module. I’ll check for voltage at the plug when the key is turned to ‘on’ (but before cranking). No voltage? The control module or wiring upstream could be the issue.
Lastly, I check for any technical service bulletins (TSBs) related to glow plug circuit issues for your specific vehicle-sometimes there are known problems or updated parts.

It’s better to have someone assist you, especially when checking for voltage, so you can safely monitor the readings while the key is cycled.

Common Mistakes when troubleshooting dtc P0672

I’ve seen folks jump straight to replacing the glow plug without checking the wiring or connectors first. That’s a surefire way to waste money if the real problem is a broken wire or a bad connection. Another common mistake is not testing the glow plug with a meter-just looking at it doesn’t tell you if it’s good. Also, don’t forget to check for blown fuses in the glow plug circuit. Skipping these steps can lead to frustration and repeat repairs.

How serious is obd code P0672

This isn’t something you want to ignore, especially if you rely on your vehicle in cold weather. If left unresolved, you could end up stranded with a no-start situation on a cold morning. Even if the engine does start, running with a faulty glow plug can cause rough running and extra stress on the other glow plugs and the control module. Over time, this can lead to more expensive repairs, including possible damage to the control module or even the battery from repeated hard starts. Honestly, things can go south quickly if overlooked.

Repair recommendations for obd2 code P0672

Here’s what usually fixes this code, based on what I see in the shop and the official repair procedures:

Replace the faulty glow plug in cylinder #2 if it tests bad
Repair or replace any damaged wiring or connectors in the glow plug circuit
Clean any corroded connections and make sure everything is tight
If the control module is at fault (no voltage to the plug), replace the glow plug control module
Clear the code and test drive to make sure the issue is resolved

Always use OEM parts for glow plugs and modules-cheap aftermarket parts can cause more headaches down the road.

Conclusion

To sum it up, P0672 means there’s a problem with the glow plug circuit for cylinder #2, which is crucial for starting your diesel engine in cold weather. It’s best not to put this off-if you do, you risk being stranded or causing more damage. Start with the simple checks: inspect the wiring, test the glow plug, and look for obvious issues before replacing parts. Most of the time, it’s a bad glow plug or a wiring problem. Get it fixed promptly for reliable starts and to avoid bigger repair bills down the line.

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