Hard starting the car only in low Morning temperatures (diesel engine)

AR9

MEMBER
2003 RENAULT MEGANE
1.5L
4 CYL
2WD
MANUAL
165,000 MILES

In low temperatures, starting from -5 and so on. The car cranks okay, but not start the engine. But if one time starts, than all the day starts without any problem. Is there any faulty sensor (crankshaft, camshaft, map sensor) or relay or fuel valve regulator that might be affected by low temperatures? I also have read that diesel becomes jelly in too low temperatures, but is there anything I could do to fix this?
What could be a problem?

3 Replies

KEN L

MASTER CERTIFIED MECHANIC
42,968 POSTS

Hello,

Diesel engines do not like starting in the cold. do you have a block heater if not I would look into installing one. Do you have a check engine light on? If so this guide will help:

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

The only other thing I can thing of is the engine coolant temperature sensor which can short out when cold.

Please run down this guide and report back.

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Thursday, December 5th, 2019 AT 11:01 AM

AR9

MEMBER
2 POSTS

No, there is no check engine light in the dashboard. It just write injection fault, but the mechanic said that they were good, and even if the dashboard indicate that as a problem, it might be something else (maybe related with any sensor)! Before 2 years my mechanic repaired the crankshaft sensor, and for one year, the car started without problem! And now again the same problem, just in winter, in low temperatures. I am really thinking of changing one or more sensors of the car, but I don't know which one to change, because the car operates really good from 0-40°C.

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Thursday, December 5th, 2019 AT 1:05 PM

KEN L

MASTER CERTIFIED MECHANIC
42,968 POSTS

I would start by changing the engine coolant temperature sensor which can be off without causing the check engine light. Here is a guide to walk you through the repair on a similar car:

https://www.2carpros.com/articles/coolant-temperature-sensor-cts-replacement

Please run down this guide and report back.

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Sunday, December 8th, 2019 AT 10:57 AM