C02 Sensor Help Please 2004 1.4 Petrol

[CharlieFarlie]

Daughters car is showing the MIL light on the dash and the garage that fitted the new thermostat last week has told daughter that is a CO2/oxygen (Are they the same ??) Sensor and it will be fine until the MOT is due in a couple of months...

Car is now getting a bit reluctant to start but once started its just fine.... Ford tell us there are two sensors one upstream and one down which I understand is just where they are in the exhaust,,

So is this sensor likely to cause the problematic starting ?

Where are they and how easy are they to get at ?

Looking on the net I can only find a generic how to which gives no indication of where the sensors are and therefore giving me no indication is this is a simple enough DIY prospect.

Garage wants £120 + VAT so near 150 quid to supply and fit the required sensor but we can buy either of the two for around 50 quid. Garage says its 1.5 hours work to do the swap... Mmmm

I have decent code reader and can switch off the light easy enough...

Thanks in advance !

Charlie.

[mintalkin]

the first sensor should be at the top of the exhaust manifold and the second just pass the cat and should be a 22mm spanner, do you know which sensor is playing up? if its the post cat one thats playing up get it fully tested as it could be the cat itself thats faulty.also check for any faulty wiring to the sensor.

[CharlieFarlie]

the first sensor should be at the top of the exhaust manifold and the second just pass the cat and should be a 22mm spanner, do you know which sensor is playing up? if its the post cat one thats playing up get it fully tested as it could be the cat itself thats faulty.also check for any faulty wiring to the sensor.

Thanks for the reply ! Are they easy enough to get at ? I have s decent kit of tools and am reasonable with them and would like to remedy the problem if I can. Garages price of 150 quid give me encouragement to do the job ! :D

If I read the codes will it identify which sensor is at fault ?

Main question is how hard are the things to get at....

Thanks again !

[stef123]

The lambda/oxygen sensors play no part in starting the car - the information from the sensors is only used once they have warmed up.

The ecu uses pre determined values

[wase16ll]

would agree with that, especially on a cold engine

taking it for granted the codes were actually read and not just guessed.

either way, if it is o2 sensor being flagged, doesnt necessarily mean it/they are faulty, more than likely its because they are trying to work but readings are out of expected range..

as an eg (not saying this is the fault)

a faulty temp sensor may cause the engine to run rich, this will be enough to throw a 02 sensor code up as its stuggling to cope with rich mixture, preventing the sensor from switching...

there might not be any code for temp sensor as although its faulty it may still be operating within its expected range...

for eg..

.a cold engine will return a 4v ref to ecu which will gradually decrease to 1v as engine warms...a faulty temp sensor may actually supply a constant 3.5v making the ecu believe engine is constantly cold so therefore increasing the fuel (choke)..no code will flag as 3.5v is within its expected range

but the 02 sensors cant switch properly untill engine is warm/hot and 'choke is off' so therefore that mil will come on with 02 flagged as the 'problem'

in a nutshell...dont take it for granted the o2 is faulty just because the code tells you..get it/them tested first otherwise you could be throwing money away

hope that makes sense

[CharlieFarlie]

Got to read the codes today and it indicated a misfire on cylinder 1 and bank sensor 1 which I believe is the first one in line and the one on the manifold...

Tried to change the plugs and the one on cylinder 1 will not come out.. It very reluctantly turned a couple of turns then went very tight and would not undo any more.. Tried 3 or 4 times and it just will not move past two turns,,,, Bugger.......

So its looking like quite a big job as I'm thinking that the head will have to come off ? Or is it possible to remove the plug in some other way ?

Any advice would be welcome !! Cheers...

[wase16ll]

could either be cross threaded or there is a build up of carbon on electrode end of plug thread.

try pouring a bit of coca cola down the recess and give it time to soak through...then tighten the plug back up, then undo a little, then tighten, loosen etc...idea being that every time you loosen, it releases a little bit more...use plenty of wd40 or coke in the process.

if plug snaps its not the end of the world, but life can get a bit more difficult...

misfire could be the problem thats causing the sensor to flag, so deal with that first before worrying about sensor as it may not return