Tip & How-To about Ford Focus

Car runs rough or cuts out when engine warms up

If your car starts perfect from a cold start then starts playing up when it reaches normal running temp, or if it even cuts out and then wont start again until the engine has cooled down then your going to need to get the following checked.

the most likely cause of your problem is going to be a bad oxygen sensor or lambda sensor for its proper name, now the reason it points towards this being the fault is that this part does not start working until the engine or exhaust is near normal running temp.
so you will find that your vehicle will start and run perfect when cold how ever as soon as the engine gets warm this part will start working and cause the car to cut out due to it sending the wrong info to the car fuel management system.

now you also need to bar in mind that this also depends on where your oxygen sensor is in your exhaust now if the sensor comes before the catalytic converter then the chances are your problem is going to be with this sensor, how ever if your sensor comes after the cat then it could also be the cat that is at fault.
if your cat comes before the sensor then it would be a good idea to have a diagnostic check done as you could spend money replacing the sensor and find out the fault it with the cat so bare this in mind when finding out the fualt

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2 Answers

vw cabrilet cuts out when driving


Hi if your car runs fine from cold and starts fine when cold, but then if it starts playing up when it gets to near running normal temp then this is a good indication that the oxygen sensor is up the shoot and will need replacing.
the reason it points towards this being the fault is that the oxygen sensor only starts to work when it reaches a certain temp so if your car runs fine when cold but plays up when hot or warm then the chances are getting the oxygen sensor (or lambda sensor for its proper name) changed should then solve your problem.

let me know how you get on or if you need further assistance ok

May 04, 2010 | Volkswagen Cabriolet Cars & Trucks

1 Answer

My 1991 chevy k1500 runs fine when cold but when it warms up it cuts out when you gas it.


hi, the problem you are having sounds to me like the oxygen sensor " or lambda sensor for its real name" has failed and needs replacing the reason it points towards this being the fault is that the oxygen sensor only starts working once the engine reaches a certain temp so if your car runs perfect from cold but plays up when warm then this is a good indication that the oxygen sensor needs replacing.

Let me know how you get on or if you need further assistance ok

Dec 28, 2009 | 1991 Chevrolet Silverado 2500

1 Answer

truck runs but cuts off after driving but will start again after sit up for a while


hi, if the truck starts and runs fine from cold but then starts playing up when it reaches normal running temp then has trouble starting untill it has cooled down if this is the case then i would say that your oxgen sensor(or lambda sensor for its proper name) needs replacing.
The reason it points towards this is that this sensor dont start working untill the engine is more or less up to temp so if this is when you start getting problems then this is what i would get changed first.

Let me know how you get on or if you need further assistance.

Dec 22, 2009 | 1993 Dodge Ram

1 Answer

ENGINE RUNS, BUT CUTOFF WHEN IT GET TO OPERATING TEMPERATURE . HAS NEW FUEL PUMP AND FUEL FILTER. THIS WAS THE PROBLEM BEFORE I CHANGED THE FUEL PUMP AND FILTER.


hi, to me the problem sounds like it could be the oxygen sensor(or lambda sensor as its proper name) the reason i say this is that the o2 sensor only starts working when the engine reaches normal runnig temp but it will run perfect from cold start so if it only plays up when the car is at or near normal running temp then the cause of the problem is going to be your oxygen sensor.

Let me know how you get on or if you need further assistance ok

Dec 14, 2009 | 1989 Pontiac Grand Am

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