Hi,

Just found out there's another issue with my car.

Turns out the piston was fine, just needed plugs and HT leads changing (leads had the date the car was made on them 08-Sept-2001, so never changed!) then get told someone's had the cat off of my exhaust, hence the engine light.

Where's the best place to get a cat from at a possible decent price?

It's a 51 plate 1.6 petrol Focus.

Thanks.

friends use these http://www.ebay.co.uk/itm/90717H-CATALYTIC-CONVERTER-CAT-FORD-FOCUS-DAW-DBW-1-6-10-1998-11-2004-2823-/200882932572?pt=UK_CarsParts_Vehicles_CarParts_SM&fits=Car+Make%3AFord|Model%3AFocus&hash=item2ec58e4b5c

with no issues and are happy with them

a catalytic convertor isnt capable of triggering an engine light, its a purely mechanical part, nothing electrical to communicate to the ecu.

in other words, the engine light has flagged up because of something else.

have the lambda sensor/s been removed too, if so, then that is what has caused the light

having said that, a cat should be fitted for mot on that age vehicle [or at least be seen to be fitted, ie..cat has just been gutted} but replacing it wont put your light out

Im afraid a cat can set the mil off by triggering a fault code a faulty cat will increase emissions triggering various sensors that monitor the co content the o2 sensors monitor how efficient the catalyst burn is if they show the same readings then the mil is triggered to indicate the cat is not functioning correctly or there is a fault with the sensor itself if the sensors are fine and the cat is faulty through a long running mis fire issue replacing the cat will cure the mil you cannot gut the cat anymore as new mot regs mean the computers checked my latest emission test shows the lambda sensor readings the maximum and minimum to which the car must be within to pass gutting the cat will give higher readings so youll fail on that now they check the mil light and find out youve switched it off so you fail for that too

sorry mate, your wrong... im pretty sure a 01 1600 only has a pre cat sensor, so ecu
will have no idea if cat is there or not and therefore not the reason
the light is lit

a faulty cat will, for eg, throw out the readings on the lambda sensor, its that sensor that will trigger the light, not the cat.

he stated that he was told the light was on because the cat was missing, makes no difference, you can put a straight pipe on, so long as lambda sensor is working correctly then the ecu will have no idea if a cat is fitted or not.

basicly, boils down to wether its a single or twin sensor, but also. not all after cat sensors monitor the cat, especially the earlier euro cars, they were just another sensor to clean up whats left...the later more sophisticated systems, did indeed trigger a light via the post cat sensor.

reason im saying is ive decatted a 2001 1.6 and it had 2 sensors once decatted it setvthe mil off and the car went into limp mode till we fitted an 02 cheater we decatted as he had a mil diagnosed by ford as the cat it had collapsed internally the first lamda takesva reading of the fumes before the cat the second takes a reading after it leaves the ecu compates both adjusting fuel mixture to maintain emissions and as of this year a cat where fitted as original equipment but missing will be a fail this can be tested applies to diesels to as i said over a year ago

Any car fitted with cat but been found to have been gutted or removed has been a failure for number of years,

Not disagreeing with you, as said, it depends if it's a single or twin sensor set up...if it's single then missing cat is not reason for engine light, twin its possible.

All 01 I have come across have had a single sensor but I know some were twin

The guy from Ford said the reason the light is on is due to a sensor saying something (emmisions?) is below threshold, due to the cat not being there?

Thats what will happen when there's no cat a new cat will sort it

again that depends on how many sensors...a single sensor cannot monitor a cat in any way, it monitors the engine emissions and adjusts them to allow the cat to work within the limits its set to.

a fully working cat will only ever reduce your emissions by an absolute max of 0.5%, its not capable or designed to reduce more than that...the emissions are set by all the other sensors/ecu.

this is why a cat will quickly fail if other sensors are'nt doing their job,

so again, it depends on how many sensors are fitted..single sensor, then its definitley nothing to do with the cat...on your model, with twin sensors, then its possible, but only if its the after cat sensor is throwing up the light

very new car being manufactured is equipped with at least one O2 Sensor
(Oxygen Sensor). This sensor was installed in vehicles starting in
1980. The O2 sensor is an integral component of the vehicle emissions
control system. Typically, it is installed in the exhaust pipe ahead of
the catalytic converter and continually analyzes the presence of oxygen
in the engine exhaust stream providing continuous data to the onboard
engine management computer to help the engine run as efficiently as
possible and to minimize vehicle emissions.


When an engine has excess fuel in the exhaust after
combustion it is described as “running rich”. On the other hand, if the
exhaust stream has excess oxygen after combustion it is described as
“running lean ”. Automotive engineers have determined an ideal ratio
of air to fuel (stoichiometric mixture) to insure the engine runs
optimally. The ideal ratio is 14.7:1, i.e. 14.7 parts of air to each
part of fuel. If the ratio is “rich” there is excess fuel which means
unburned fuel in the exhaust stream and therefore excessive emission
pollution. On the other hand, if the ratio is “lean” the result is more
nitrogen-oxide pollutants which can cause poor performance and even
result in engine damage.



Located in the exhaust pipe, the O2 sensor is capable of
detecting whether the engine is running “rich” or “lean”. It does this
as a result of a chemical reaction in the sensor that generates voltage
proportionate to the stoichiometric mixture. The engine’s computer
monitors the voltage from the O2 sensor and automatically adjusts the
amount of fuel entering the engine based upon whether the mixture is
rich or lean.
Because there are a number of factors that can influence
the oxygen content in air, the O2 sensor must be working properly at
all times so the engine operates with the proper air/fuel ratio. Some
of the factors that can influence oxygen content are; altitude, air
temperature, engine temperature, barometric pressure and the load on the
engine.


If the O2 sensor fails, the engines computer can
no longer sense the actual air/fuel mixture so it ends up “guessing”
which causes your car to perform poorly and to consume more fuel than it
needs to.


As a result, a defective O2 sensor can contribute to pre-mature catalytic converter failure.