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sean, Ford Technician
Category: Ford
Satisfied Customers: 3105
Experience:  Ford Master Technician.
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Hi im after some advice on a 2000 ford focus 1.6, its failed

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Hi im after some advice on a 2000 ford focus 1.6, its failed on emissions again on the following.
1. exhaust emissions carbon monoxide content after 2nd fast idle excessive
2. exhaust emissions hydrocarbon content after 2nd fast idle excessive
3. exhaust emissions lambda reading after 2nd fast idle outside limits
last year I had similar issues and made the following changes, sensor change before the cat (there isn't a sensor after cat) oil change, spark plugs, air filter, breather hose behind the inlet manifold this was split....this then passed the MOT although the second fast idle test says not tested?!?! this year its failed on all 2nd fast idle...the MOT guy says its probably the CAT as its an aftermarket product. any ideas on what to change would be a great help. Just another note the car during the year drives very little and not very far each day. Thanks Paul
Hello, I hope I can be of assistance.
First with regard to the MOT if the emissions fail the first fast idle test then the tester has to run the engine at speed for a few minutes then test the emissions again only after failing the second test can it be classed as an MOT fail.
If the emissions pass the first test then there is no need to test a second time which is why it states second fast idle not tested.
You don't give any readings as to how far the figures were outside their limits but to be honest 9 out of 10 aftermarket catalysts are OK for the MOT emission test, in my experience the only problems with aftermarket catalysts tend to be on the later cars with a post cat. sensor giving catalyst efficiency concerns due to the smaller surface area of the catalyst compared to a genuine catalyst (they are cheaper for a reason) this brings the MIL on but the emissions still tend to be below an MOT fail.
Check for any air leaks, given the mileage the car does clean the spark plugs and then test to see if the HEGO sensor is switching or if the voltage stays the same. It's possible that the HEGO has failed so check that there is 12 volts and an earth to the heater on it. This engine does have concerns with injectors leaking causing excess fuel, a sign of this is poor starting when hot and a slight misfire on start up but it goes away if the engine is revved a couple of times.
Start with these points, let me know if you have more questions regarding this and I'll reply as soon as I'm able to.
Best wishes,
sean and other Ford Specialists are ready to help you
Customer: replied 3 years ago.

Hi Sean,

Thanks for getting back to me and explaining. The Emissions this year are the following :-

fast idle : cO = 3.88 , HC = 455 , Lambda = 0.890

Second Fast idle : CO = 6.25 , HC = 704 , Lambda = 0.826

Natural Idle : CO = 0.99

I will check what you have suggested with plugs etc, the car starts perfectly and never misfires in fact it drives very well, im not sure from the readings above how serious it is or whether a service will bring the readings down again like last year?

Many Thanks


Hello again,
the CO and HC high and Lambda low would suggest a rich mixture, usually a cat. fault gives a high Lambda reading, from memory the Focus should be between 0.95 to 1.05 and the CO should be below 0.3 but is usually nearer 0.1.
You can try changing the oil and checking the spark plugs first, use a good quality 5/30 oil.
The other thing I mentioned is checking the HEGO as if this doesn't work then the emissions will always be incorrect.
Unless the engine is smoking excessively this isn't going to be anything serious, an after market HEGO can be bought for no more than £50.
Let me know if I can advise further.
Best wishes,
Customer: replied 3 years ago.

Hi Sean

Thanks for the reply again, ok what I will do is do the service oil and plugs. When you say HEGO I am assuming that this is the Lambda sensor pre cat (this car has only 1 sensor) I did replace it last year and the car went through the MOT , I can test or replace it perhaps it went wrong?

I don't think its major its just a pain all these emissions! I do have a ODBC2 connector so was wondering if any software can check emissions...will this also say if the sensor has failed?

Many thanks


Hello again,
yes the HEGO is the Lambda I just use Ford terms, the EOBD scanner should pick up if there is a concern with the sensor but you can use a multi meter as well to check the voltages, the heater has 12 volts and earth and the switch wires should go between 0.1 to 0.9 volts.
Customer: replied 3 years ago.

Thanks again Sean much appreciated



No problem, you can open this thread back up if you need to.