MOT emissions failure advice please..
Discussion
Hello I have a Ford focus 2.0 (2005) which has done 78000 miles. I recently put it in for an MOT and has failed pretty badly on emissions, I have very limited knowledge on this topic and was hoping somebody could give me a bit of advice please? This is the copy of test results. As the car is obviously of limited value anyway due to its age, would trying to repair it be cost effective or would it probably be more than the car is actually worth on paper? Thanks for any advice..Lena
What that is saying is that there is a lot of unburnt fuel going through the engine into the exhaust
Could be a lot of things, a sensor, plugs, blocked air filter. Suggest it needs a good looking at but depending on the car a obd device could tell you a lot, do you know someone who could do an obd diagnostic on the car?
The obd devices can be really cheap. I bought a reasonable one that works with a Bluetooth phone for £2.99!
Could be a lot of things, a sensor, plugs, blocked air filter. Suggest it needs a good looking at but depending on the car a obd device could tell you a lot, do you know someone who could do an obd diagnostic on the car?
The obd devices can be really cheap. I bought a reasonable one that works with a Bluetooth phone for £2.99!
Everything points to it running rich, and I agree with the other suggestions that a faulty lambda sensor could cause this. But it might just be struggling with dirty plugs. You don't mention when it was last serviced. If it wasn't recent, I'd put some clean plugs and an air filter on and try again.
Hiya thanks for the replies, also I forgot to mention that the Amber engine management light is lit in the dash too. Unfortunately I don't know anybody who knows much about cars, I have move to a new area so I'm pretty much relying on the mechanics at the garage, they said they would book it back in but when I asked what it was likely to be they said it could be anything so I asked for a figure and he said he wouldn't like to say which lead me to believe I was looking at a hefty bill, hence why I am considering whether it would be cost effective.
Hi to be honest it hasn't been serviced for a long time, I know that is asking for trouble and really should be more responsible regards servicing. Going by your replies I have just booked it in to a garage close to home to get it looked at in more detail tomorrow morning. Thanks for your help
I suggest you ask them to diagnose the fault and let you know what it's likely to cost to fix. Obviously they will need to work on the car to do that and will want paying, but they should be able to give you a budget for that and I doubt it will be very expensive just to read the fault codes and do some basic fault finding on the engine sensors. Don't count your chickens, but if it's something simple like a failed lambda sensor you might be looking at an hours labour and a hundred quid in parts to diagnose and fix.
Thank you.. to be honest I expect to be paying to get through an MOT simply due to the cars age etc and anything up to £300-£400 would warrant getting it done simply so I can use the car get to work etc. I will see what the garage says and keep my fingers crossed. Thanks again for everyone's help
A couple of years ago I gave you all an equation which calculates the expected MOT lamdba value to within a couple of percent from the CO reading assuming no air leaks in the exhaust system.
https://www.pistonheads.com/gassing/topic.asp?t=15...
Lambda value = (14.5-(CO% x 0.37))/ 14.6
In this case we have CO of 2.987 which gives us a calculated lambda of 0.917 - actual 0.909 so spot on within 1% or so
Second reading 4.812 which gives us a calculated lambda of 0.871 - actual 0.857 so again about spot on.
So we can tell from this the exhaust system is good and the engine is actually burning just the air and fuel coming in from the inlet side. However, to the OP, be a bit wary of the advice you're seeing here. The lambda sensor in the car is just a feedback system to correct small errors in the ECU's base map. Even if the lambda fails there has to be something to cause the mixture to go very rich in the first place. Most likely cause is a failed coolant temperature sensor. These are easy to check and cheap to replace compared to most other things. If the ecu thinks the car is stone cold it will "put the choke on" and squirt in a lot more fuel. Now a good lambda sensor should try and correct this so it may well be that sensor has also failed but I'd first look at the coolant sensor and see what happens. The failed coolant sensor probably won't throw up a fault code so the average clueless garage mechanic won't see this on a code reader and will be unlikely to understand anything that doesn't show a code.
Your test results tell you nothing about the CAT so leave this until absolute last. Coolant sensor first, lambda sensor second, CAT only if there's still a problem.
https://www.pistonheads.com/gassing/topic.asp?t=15...
Lambda value = (14.5-(CO% x 0.37))/ 14.6
In this case we have CO of 2.987 which gives us a calculated lambda of 0.917 - actual 0.909 so spot on within 1% or so
Second reading 4.812 which gives us a calculated lambda of 0.871 - actual 0.857 so again about spot on.
So we can tell from this the exhaust system is good and the engine is actually burning just the air and fuel coming in from the inlet side. However, to the OP, be a bit wary of the advice you're seeing here. The lambda sensor in the car is just a feedback system to correct small errors in the ECU's base map. Even if the lambda fails there has to be something to cause the mixture to go very rich in the first place. Most likely cause is a failed coolant temperature sensor. These are easy to check and cheap to replace compared to most other things. If the ecu thinks the car is stone cold it will "put the choke on" and squirt in a lot more fuel. Now a good lambda sensor should try and correct this so it may well be that sensor has also failed but I'd first look at the coolant sensor and see what happens. The failed coolant sensor probably won't throw up a fault code so the average clueless garage mechanic won't see this on a code reader and will be unlikely to understand anything that doesn't show a code.
Your test results tell you nothing about the CAT so leave this until absolute last. Coolant sensor first, lambda sensor second, CAT only if there's still a problem.
Lenalou said:
Hiya thanks for the replies, also I forgot to mention that the Amber engine management light is lit in the dash too. Unfortunately I don't know anybody who knows much about cars, I have move to a new area so I'm pretty much relying on the mechanics at the garage, they said they would book it back in but when I asked what it was likely to be they said it could be anything so I asked for a figure and he said he wouldn't like to say which lead me to believe I was looking at a hefty bill, hence why I am considering whether it would be cost effective.
Because it could be anything...but at least there is a warning light that might help to steer them in the right direction.The problem is not in particular unburnt fuel though, it's just running a little rich. Hydrocarbons will come down when CO also comes down.
Usual...check lambda sensor, and general servicing is in good order.
Thank you all so much for all your help. For somebody who knows nothing about the mechanics of a car this forum and everyone on here who takes their time to help are an absolute god send. I will keep my fingers and toes crossed for tomorrow when I take it to the garage and will post back to update on how I get on.
Thanks..Lena
Thanks..Lena
Just to "help things out" an oil & filter, air filter, and plug change wouldn't do any harm if it hasn't been serviced in a while.
A few years ago a friend came to me with similar results & had been told to change the cat & lambda sensor, after a service as above & a good run it passed with almost perfect readings.
A few years ago a friend came to me with similar results & had been told to change the cat & lambda sensor, after a service as above & a good run it passed with almost perfect readings.
The fact you have a CEL is good, it means the code can be read and the problem traced. In my experience Lambda sensors seem to die around the 100K mark so good shout for the person who said it could also be a water temperature sensor.
If you are going to fit new sensors then I would personally only buy a brand you have heard of (Bosch etc.) and avoid the cheap Chinese knock offs. The might be less than half the cost but you will be replacing it again in less than a year.
Good luck, I am sure it is something simple to fix.
If you are going to fit new sensors then I would personally only buy a brand you have heard of (Bosch etc.) and avoid the cheap Chinese knock offs. The might be less than half the cost but you will be replacing it again in less than a year.
Good luck, I am sure it is something simple to fix.
Lenalou said:
Hiya just an update.. I put the car into the garage today and they phoned to say there is a split in the intake manifold which is causing the high revs and altered readings in the emissions, they quoted £240 to replace it as it is a 3 hour job. They said it will be ready tomorrow.
Little worried about this. A split in the intake would cause a very weak mixture to run through your engine, You have a very rich mixture running through your engine.Secondly a visual inspection seeing a split in an intake could be easily plugged and then see if this cures the car on a temporary basis to give confirmation to the money the punter was about to spend. The fact that they are going to start replacing things without any attempt to test or tell you what the EML light on your dashboard means gives me the impression this garage is one of those 'replace till it works' rather than give an accurate diagnosis places.
Only a feeling and might not have all the information here.
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