Top Reasons Why Heater Plugs Fail in Diesel Cars – Symptoms & Fixes

Heater plugs (glow plugs) are essential in diesel cars for cold starting. Learn the main reasons they fail and how to detect and replace faulty glow plugs in time.

🔧 Introduction

In diesel engines, heater plugs (also known as glow plugs) play a crucial role in ensuring smooth cold starts. These components preheat the combustion chamber so that fuel can ignite easily. However, over time, they can fail due to various reasons, leading to difficult starts, white smoke, and poor engine performance. In this article, we’ll explore the top reasons why heater plugs fail in diesel cars, signs to watch for, and how to fix or replace them.

🔍 Top Reasons Why Heater Plugs Fail

1. Carbon Build-Up

One of the most common reasons for heater plug failure is carbon deposits. Over time, carbon accumulates on the plug tips, reducing their heating ability.
Tip: Regular engine servicing can help minimize carbon build-up.

2. Excessive Voltage

A faulty relay or control module may send too much voltage to the glow plugs, causing them to burn out prematurely.
Solution: Always test the glow plug control unit if plugs fail frequently.

3. Age & Wear

Glow plugs are wear-and-tear items. Most last between 60,000 to 100,000 km. Beyond this, they may weaken or break.
Recommendation: Replace all glow plugs at once during maintenance.

4. Oil or Fuel Contamination

If engine oil or fuel leaks into the combustion chamber, it can contaminate and damage the heater plugs.
Sign: You may notice oil on the plug tip during inspection.

5. Poor Quality Parts

Using non-genuine or low-quality glow plugs often leads to early failure. Always buy high-grade or OEM spares.
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🚗 Symptoms of Faulty Heater Plugs

• Trouble starting your diesel car in cold weather

• White smoke from the exhaust during start

• Engine misfiring

• Dashboard warning lights (Glow Plug or Check Engine)

• Increased fuel consumption

🛠️ How to Fix or Replace Heater Plugs

1. Diagnose using an OBD scanner for any DTC codes related to glow plugs (like P0671, P0672).

2. Test each glow plug’s resistance using a multimeter (should read around 0.6–2 ohms).

3. Replace all glow plugs together to ensure even heating.

4. Use OEM or high-quality used parts from trusted sellers.

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🛒 Where to Buy the Best Heater Plugs Online in India?

At NayaPuranaOnline.com, you can find new and used heater plugs at affordable rates. We ensure quality, tested parts for brands like:

• Tata Motors

• Mahindra

• Hyundai

• Maruti Suzuki

• Toyota

• Ford & more

🔗 Useful Internal Links

• 🔧 How to Choose the Right Heater Plug for Your Diesel Car

• 💡 Signs Your Car’s Glow Plug Needs Replacement

• 🚘 Top Diesel Engine Car Parts Online

✅ Conclusion

Heater plug failure is a common issue in diesel cars, especially during winters. By understanding the causes and recognizing the early signs, you can avoid starting problems and engine wear. Whether you need affordable used glow plugs or brand-new OEM parts, NayaPurana has you covered!