P0384
Fix within a few daysGlow Plug/Heater Circuit 'D' Malfunction
Code P0384 means Glow Plug Circuit D is faulty. Common causes: Faulty Glow Plug D (70%), wiring issues (15%), GPCM (10%). Drivability: Yes, but expect hard cold starts. Repair cost: $20-$300 DIY, $150-$800 professional.
Can I Drive With P0384?
Yes, for short trips only
Essential trips under 10 miles, avoid highways if engine runs very rough
Stop driving immediately if: Engine fails to start, excessive white smoke, or significant power loss.
Symptoms of P0384
- 1Hard starting, especially in cold weather
- 2Rough idle immediately after starting
- 3White smoke from exhaust on startup
- 4Check Engine Light is on
Common Causes of P0384
Parts most likely causing this code, ranked by probability
A faulty glow plug 'D' is the most common reason for a circuit malfunction in its specific circuit.
70% of P0384 cases are fixed by replacing this part
Corroded, damaged, or loose wiring or connectors can interrupt the electrical circuit to glow plug 'D'.
15% of P0384 cases are fixed by repairing wiring or connectors
The GPCM controls the power to the glow plugs; a fault within the module can cause a specific circuit malfunction.
10% of P0384 cases are fixed by replacing the GPCM
A blown fuse or faulty relay in the glow plug circuit can prevent power from reaching glow plug 'D'.
5% of P0384 cases are fixed by replacing a fuse or relay
Check These First (Before Buying Parts)
- Visually inspect the wiring and connector for glow plug 'D' for any obvious damage, corrosion, or looseness.
- Check the glow plug fuse and relay in your vehicle's fuse box (consult your owner's manual for location).
How to Diagnose P0384
- 1Visually inspect glow plug 'D' wiring and connector for damage or corrosion.
- 2Check the fuse and relay for the glow plug circuit (refer to your vehicle's fuse box diagram).
- 3Test the resistance of glow plug 'D' with a multimeter (should be very low, typically under 1 ohm).
- 4With the engine cold, check for voltage at the glow plug 'D' connector when the ignition is first turned on (should be battery voltage for a few seconds).
- 5If glow plug 'D' and its wiring are good, test the Glow Plug Control Module (GPCM) for proper operation.
P0384 on Popular Vehicles
Ford F-250/F-350
2003-2024Powerstroke engines are known for glow plug failures, especially in older models. Access to glow plugs can be difficult due to tight engine compartments. The Glow Plug Control Module (GPCM) is also a common failure point.
75% fixed by replacing glow plug 'D' or GPCM
Ram 2500/3500
2003-2024Cummins engines typically have robust glow plug systems, but individual glow plugs can fail over time. Wiring corrosion, especially in areas exposed to road salt, can also trigger P0384.
80% fixed by replacing glow plug 'D' or repairing wiring
Chevrolet Silverado/GMC Sierra 2500/3500
2001-2024Duramax engines can experience P0384 due to failed glow plugs or issues with the glow plug controller. It's important to check for oil leaks around the glow plug harness, which can degrade wiring.
70% fixed by replacing glow plug 'D' or GPCM
Frequently Asked Questions
What does P0384 mean?
P0384 indicates a malfunction in the electrical circuit for glow plug 'D'. This typically means the engine's computer isn't seeing the correct electrical resistance or voltage from that specific glow plug.
Can I drive with P0384?
Yes, you can drive with P0384, but expect hard starting, especially in cold weather. The engine will likely run rough for a short period after starting. Fix this within a few days to avoid further issues.
Will P0384 clear itself?
No, P0384 will not clear itself. The underlying electrical fault with the glow plug or its circuit must be repaired for the code to clear. After repair, you may need to clear the code with an OBD-II scanner.
How do I fix P0384 myself?
Start by visually inspecting the wiring and connector for glow plug 'D'. Check the glow plug fuse and relay. If those are good, test the resistance of glow plug 'D' with a multimeter. If it's faulty, replace the glow plug. If the glow plug is good, you'll need to test the Glow Plug Control Module.
How much does it cost to fix P0384?
DIY repair costs range from $20-$300, primarily for a new glow plug ($20-$50 each) or a Glow Plug Control Module ($100-$300). Professional repair costs typically range from $150-$800, including parts and labor, depending on whether it's a single glow plug or the control module.
P0384 keeps coming back - why?
If P0384 keeps returning, it means the root cause was not fully addressed. Common reasons include: a faulty Glow Plug Control Module that was overlooked, a persistent wiring issue, or another glow plug in the same circuit failing shortly after the first repair.
Will P0384 fail emissions/smog test?
Yes, P0384 will cause your vehicle to fail an emissions or smog test. A Check Engine Light for any powertrain code, including P0384, is an automatic failure in states with emissions inspections.
What's the difference between P0384 and P0380?
P0384 specifically points to a malfunction in the circuit for glow plug 'D'. P0380 is a more general code indicating a malfunction in the overall glow plug/heater circuit, without specifying a particular glow plug.
P0384 on Ford F-250?
On a Ford F-250 (Powerstroke diesel), P0384 often points to a failed glow plug 'D' or a wiring issue to that specific glow plug. Accessing the glow plugs can be challenging due to engine layout, but the diagnostic steps remain the same. The Glow Plug Control Module (GPCM) is also a known failure point on these trucks.
Questions to Ask Your Mechanic
Did you test the resistance of glow plug 'D' and check for voltage at its connector?
Good answer: Yes, I measured the resistance of glow plug 'D' and it was out of spec/open, or I found no voltage getting to the plug when commanded on.
What did you find when inspecting the wiring and connector for glow plug 'D'?
Good answer: I found corrosion/damage on the connector, or the wire insulation was chafed, causing an intermittent open circuit.
Did you test the Glow Plug Control Module (GPCM) for proper output to circuit 'D'?
Good answer: Yes, I confirmed the GPCM was not sending power to glow plug 'D' even when commanded, indicating an internal fault in the module.
Repair Cost Estimate
DIY Repair
Parts only
$20-$300
Shop Repair
Parts + labor
$150-$800
Save $130-$500 by doing it yourself
Difficulty
intermediate
Time
1-3 hours
Intermediate - requires a multimeter for testing and careful removal of glow plugs to avoid breakage, which can be challenging.
Cost of Waiting
Ignoring P0384 will lead to increasingly difficult cold starts, especially in winter. This puts extra strain on your starter and battery, potentially leading to premature failure of those components. It also increases harmful emissions and can cause unburned fuel to wash down cylinder walls, diluting your engine oil.
While You're In There...
If one glow plug has failed, others are likely to follow soon, especially if they are original. Replacing the set prevents repeat labor and ensures consistent cold starting performance.
Apply dielectric grease to electrical connectors to prevent corrosion and ensure a good electrical connection, especially in harsh engine environments.
Tools You'll Need
- OBD-II scanner
- Multimeter
- Socket wrench set
- Glow plug socket (often a specialized thin-wall socket)
- Wire brush (for cleaning connections)
P0384 is a common issue on diesel engines, especially as they age. Most repairs involve replacing a single glow plug, which is a straightforward fix that will restore your engine's reliable cold starting.
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Your Next Steps
Step 1: Perform a thorough visual inspection of glow plug 'D' and its wiring/connector. Look for frayed wires, melted insulation, or heavy corrosion.
Step 2: Check the relevant fuses and relays for the glow plug circuit. Replace any blown fuses.
Step 3: If visual inspection and fuse checks don't reveal the problem, use a multimeter to test the resistance of glow plug 'D'. If it's open or has very high resistance, replace the glow plug.