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P0384 Fault Code


You can find information about the P0384 fault code on this page.

We have given it a seriousness of 6/10 with 1 being the least serious and 10 being the worst.

P0384 Short Description

"Glow Plug/Heater Circuit B"

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Description Icon Long Description

Fault P0384 is logged when the engine control module (ECM) has detected an issue with the glow plug heater circuit.

This happens when the voltage signal from the circuit is higher than the predetermined allowable range.

Unlike petrol engines, diesel engines do not rely on spark plugs for ignition. Instead, they use the heat generated from the compression cycle to cause combustion.

At low engine temperatures and cold environments, there is not enough heat generated in the beginning to ignite the air-fuel mixture. Glow plugs are used to warm the cylinders to aid in the first few cycles when starting the engine.

This means only diesel engines will have glow plugs and be able to have this fault code logged.

Again, this fault code can only be found in diesel vehicles. Manufacturers like Audi and Volkswagen, as well as Ford, can be some of the most commonly searched associated with this fault code.

Warnings Icon Other Signs of This Problem

Issues involving glow plugs can cause similar symptoms to issues with spark plugs. However, these are typically relegated to the starting of the engine rather than during continuous running.

The Check Engine light will be one of the most obvious tools in diagnosing this issue. Another warning light can be the Pre-Glow light. This light may not illuminate at all or remain illuminated after starting.

There may be other glow plug-related issues that present themselves when starting the vehicle.

These can be things like the engine struggling to start, particularly in colder weather as the glow plugs are not functioning properly.

It is very likely that the engine will struggle to start. Upon starting, it is likely that the exhaust pipe will emit white smoke.

It is possible for other glow plug fault codes to be logged. These can be codes like P0380, P0381, and P0640.

Broken Down Icon What Could Be The Problem?

There are several potential causes for this issue. These will typically be found within the glow plug system, causing a high voltage.

It is possible that there is a faulty glow plug within the system. Additionally, a faulty glow plug relay could be the cause. The glow plug relay is responsible for controlling the operations of the glow plugs.

Damaged wires or loose connections can also lead to electrical issues like this within the glow plug system.

Another electrical issue could be a blown fuse in the glow plug heater circuit.

Fixed Icon Fixes

The majority of the fixes for this issue will be electrical in nature. Otherwise, they will likely require changing faulty parts in the glow plug system.

Damaged electrical components like frayed wires or connections need to be fixed. Blown fuses need to be replaced.

Any faulty glow plugs need to be replaced.

Open or short circuits in the glow plug heater circuit need to be fixed.

A faulty glow plug relay needs to be replaced.

Danger Icon Seriousness

Fault code P0384 should be considered a moderately serious issue. It can severely hamper the driveability of the engine, particularly in colder climates where glow plugs need to operate perfectly.

It is best to have this issue fixed as soon as possible or immediately if the engine will not start.

P0384 Image

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