Skip the auto shop - Our mechanics make house calls

Q: idling problem with peugeot 406

asked by on

My peugeot 406 has a problem with idling wen its cold lyk mornings...wen it hots up it runs smoothly

A: Hello and thank you for contacting YourMech...

Hello and thank you for contacting YourMechanic. When you start the engine up when it is cold and the engine idles rough or does not want to stay running, then this is an indication that the engine temperature sensor has failed. When the engine is started cold, the engine temperature sensor sends a signal to the computer to provide a richer mixture. As the engine temperature sensor begins to fail, it sends a higher than actual temperature signal to the computer. The computer leans the fuel mixture thinking the engine is at normal operating temperature. This will cause the engine to run rough. As the engine warms up, it not longer needs the richer cold idle mixture and the engine begins to run smoother. I recommend replacing the engine coolant temperature sensor. If you need further assistance in diagnosing your vehicle, then seek out a professional, preferably a YourMechanic professional to help you with your vehicle.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Car misfires while idling

If you think your car is misfiring, you should have a Check Engine light up on the dash. If you have a Check Engine light, start by having the vehicle scanned for trouble codes. If any cylinder is misfiring, the...

Q: Vehicle dies at idle while driving

It is very possible the knock sensor could cause this issue. However, before replacing the knock sensor the vehicle's timing should be checked. If the timing is retarded it will cause the vehicle to die when dropped to an idle....

Q: Takes 3-7 tries before engine stays running

Hello. The symptoms you are experiencing, hard starting and an unstable idle speed, can be caused by a variety of issues. You mention that you replaced a few parts, namely ignition components, so they should be alright. The next things...

Related articles

How to Avoid Back Pain in a Car
If you have back problems, sitting in a car for an extended period of time can be excruciating. Even without back problems, you could experience discomfort and soreness from...
What are the Car Pool Rules in Hawaii?
Hawaii is widely regarded as a land of vacation and relaxation, and as such, its scenic roads and routes are far better known than the state’s freeways. But, as with all...
How Much Does a Mechanic Make in Vermont?
Automotive technician jobs in Vermont have an average mechanic salary of $37k, with some mechanics earning a salary of $53k.