Why is the glow plug light flashing on my Ford Transit?

A flashing glow plug light on a Ford Transit usually signals a fault in the diesel glow plug system or a related engine management issue that needs diagnosing.

In Ford Transits, which commonly use 2.0 EcoBlue or 2.2 TDCi diesel engines, the glow plug indicator appears during preheat to assist cold starts. If it flashes, the vehicle’s engine control unit has detected an issue in the glow plug circuit or an associated system, and it may also point to broader engine or emissions-related faults. A diagnostic read with an OBD-II scanner is recommended to pull trouble codes and guide the next steps. Electrical issues, battery voltage, or faulty sensors can all trigger a flashing glow plug light, so a systematic check is wise.

Common causes of a flashing glow plug light

The following are the most frequent reasons a Ford Transit might show a flashing glow plug indicator. Understanding these helps you decide whether to attempt a quick check or take the van to a shop.

• Faulty glow plugs or a failing glow plug relay/control module



• Low battery voltage or charging system problems that prevent adequate preheating


• Engine sensors or ECU faults causing the glow cycle to be skipped or misinterpreted


• Electrical faults in the glow plug circuit such as blown fuses or faulty wiring harnesses


• Emissions or engine management issues (for example, intermittent misfires or DPF-related faults) that trigger the warning as part of a broader check engine signal

These failures can vary by model year and engine type, so reading the exact fault codes is crucial to pinpointing the root cause.

What to do if the light keeps flashing

If you notice the glow plug light flashing, follow these steps to assess safety and identify the cause without risking more damage to the engine.

1. Safely pull over if you are driving and the engine starts running roughly or you feel loss of power. Turn off the engine and inspect for obvious issues.


2. Read the onboard diagnostic codes with an OBD-II scanner. Note any glow plug-related codes (for example, P0671–P0676 are typically glow plug circuit codes) or generic codes like P0380. These codes help point to the exact circuit or component.


3. Check the battery and charging system. A weak or failing battery can prevent proper preheat and trigger warning lights. If possible, test voltage (a healthy battery should show about 12.6 volts with the engine off and higher when the engine is running).


4. Inspect the glow plug wiring and connectors for signs of wear, corrosion, or damage. Look for melted insulation, loose connections, or worn pins.


5. If the light remains flashing after a basic check, or if you notice misfires, rough running, or poor starting, schedule service with a qualified technician or a Ford dealer. A professional can perform a more thorough diagnostics, including glow plug resistance testing and wiring harness inspection, and update or repair the ECU/controls if needed.

Continuing to drive with a flashing glow plug light, especially if the engine shows rough running or reduced power, can lead to increased fuel consumption, damaged injectors, or costly repairs. Getting a timely diagnosis is the safest course.

Diagnosing and addressing common scenarios

To help you navigate typical situations, here are practical notes on common scenarios you might encounter with a flashing glow plug light on a Ford Transit.

• If the light only flashes during cold starts in very cold weather and disappears once the engine warms, it might indicate the preheat cycle is being sensed as excessive or insufficient by the control module, still warranting a check if the issue recurs.


• If the light is flashing even after a successful startup and the engine runs normally, you should still have the codes read to confirm no knock or misfire-related concerns.


• If the vehicle enters limp mode or experiences noticeable power loss, treat it as a urgent fault and seek immediate testing to avoid damage to the exhaust aftertreatment system or turbo/injector components.

Regular maintenance, including periodic glow plug checks as part of a diesel service, can reduce the likelihood of unexpected flashing lights and ensure reliable cold starts.

Summary

A flashing glow plug light on a Ford Transit typically signals a fault in the glow plug system or a related engine management issue. Common causes include faulty glow plugs or relays, damaged wiring, low battery voltage, and ECU or sensor faults. Start with a diagnostic code read, inspect electrical connections and battery health, and seek professional help if the light persists or if you notice engine performance issues. Timely diagnosis can prevent further damage and keep your Transit running reliably.

What are the symptoms of a bad glow plug control module Ford?

Symptoms of a bad Ford glow plug control module (GPCM) include hard starting, especially in cold weather, a rough idle, and white smoke from the exhaust. Other signs are poor engine power, reduced fuel efficiency, and the check engine light being illuminated. 
You can watch this video to learn about the symptoms of bad glow plugs: 49sEasyAutoFixYouTube · Jan 25, 2025
Common symptoms

• Hard starting: The engine struggles to start, particularly in cold temperatures, because the glow plugs aren't providing enough heat to ignite the fuel. 
• Rough idle: The engine may shake or run unevenly right after starting until it warms up, due to inconsistent combustion in some cylinders. 
• White exhaust smoke: Unburned fuel is expelled from the exhaust, which is most noticeable during and immediately after startup in cold conditions. 
• Poor engine performance: You may experience a loss of acceleration and overall engine power. 
• Decreased fuel efficiency: The engine burns more fuel to compensate for the lack of heat from the glow plugs. 
• Check engine light: The warning light on the dashboard often indicates a problem with the glow plug system. 

Why is the glow light flashing on my Ford Transit?

Glow Plugs Warning Lamp
If the glow plug light remains constantly lit or flashes, it's likely that the glow plugs and/or relay switch require replacement.

Can I still drive with the glow plug light flashing?

You can drive with a flashing glow plug light, but it's not recommended, especially for long distances or highway speeds. A flashing light indicates a fault in the glow plug system or another issue like a burnt-out brake light that can cause the light to flash. Continuing to drive can lead to reduced engine performance, poor fuel economy, or potential engine damage.
 
This video explains what to do when your glow plug light is flashing: 50sDashboard warning lights YouTube · Nov 6, 2022
Why you shouldn't drive long distances

• Reduced performance: The vehicle may enter a "limp mode" with significantly reduced engine performance to prevent further damage. 
• Increased engine damage risk: Continued driving with a faulty system can lead to further component damage or a misfire. 
• Poor fuel economy: You will likely experience a decrease in fuel efficiency. 

What you should do

1. Check your brake lights: A simple and common cause for a flashing glow plug light is a burnt-out brake light bulb. If a brake light isn't working, replace the bulb and the light should turn off. 
2. Drive cautiously: If you must drive, do so at reduced speeds and avoid highways. 
3. Get the codes read: Use an OBD-II scanner to read the diagnostic trouble codes (DTCs) and identify the exact cause. 
4. Seek professional diagnosis: Have a qualified mechanic diagnose and fix the problem as soon as possible. 

What does it mean when the glow plug light is blinking?

A flashing glow plug light indicates a problem with the engine, often a fault in the glow plug system, and requires immediate attention. Unlike a solid light that means the engine is preheating, a flashing light signals a malfunction that could lead to serious engine damage if ignored. It is advised to get the vehicle diagnosed with a scan tool to read the error codes and determine the exact issue.
 
This video explains what the glow plug light means: 41sAsk A MechanicYouTube · Oct 31, 2022
Possible causes for a flashing glow plug light

• Faulty glow plugs or glow plug relay: Over time, glow plugs can wear out, or the relay that powers them can fail, triggering the light.
• Engine management system issues: Problems with the engine control unit (ECU) or a malfunctioning sensor, such as the crankshaft or camshaft position sensor, can cause the light to flash.
• Diesel Particulate Filter (DPF) problems: A clogged or malfunctioning DPF can trigger the warning light.
• Fuel injection system issues: A blocked injector or a failing fuel pump can also cause a flash.
• Wiring or electrical faults: Problems with the wiring or other electrical components connected to the glow plug system.
• EGR valve failure: A failed or clogged Exhaust Gas Recirculation (EGR) valve can trigger the warning light. 

You can watch this video to learn more about potential causes of a flashing glow plug light: 59sDashboard warning lights YouTube · Jul 29, 2024
What you should do

1. Pull over safely: Do not ignore the light, as driving with it could cause significant engine damage. 
2. Consult a mechanic: Have a diagnostic scan tool read the error codes to pinpoint the exact problem. 
3. Get the issue diagnosed and repaired: Address the underlying cause of the flashing light, which could range from a simple repair to a more complex one involving the engine management system.