Ford Fiesta zetec s Failed mot emissions badly

[Zetec x]

Hi all 1st time posting this. HELP. Any advice. Had Lambda sensor but not helped.

 

[scotman]

This being a north American Fiesta site, i don't think that many of us can offer advice. The MOT emissions test you failed doesn't have the stated limits of the standard. Did the test facility offer to do a quote for a repair?
I am aware that the government has expanded upon ulez areas( which i understand involved predominantly London) that might affect registration levels of certain vehicles. You have tagged yourself as being in Cumbria., a very rural region.
You dont mention any issues with your Fiesta beyond the O2 sensor. Or its odometer reading. The test facility should have offered some insight! If catalyst efficiency was below threshold that would have been mentioned. That low oil temperature readout in the report would be the first and only tipoff to me that you might be dealing with a failed sensor OR sensors. Which should have set a malfunction indicator lamp. But again, we don't have that information.

 

[Handy Andy]

High CO emission? - if I may...

Can mean several events taking place, all dealing with poor combustion.

So the O2 sensor and it's AFT (rear sensor) work together to determine a course of action - a direction to take. If all within tolerance the engine thinks all is normal - but this too is a tolerance issue - short runs is hard on a high mileage (Km) motor doesn't get hot enough to burn off the petrol fumes caught up in the oil and intake manifold so it won't set a light on the dash by itself but the continuous short trips can cause some device to plug up and then set the light.

If you have not done an oil change on a consistent basis - the wear and tear on the cylinder walls from old oil can wear down the oil sealing rings to keep combustion charge (Fuel burned to exhaust) stuff in the combustion chamber and not blow by those ring seals and flood the crankcase with exhaust and partly burnt oil . But as you drive the chambers have a chance to ventilate and clear out - so by even a long drive in from the country can then make the monitors think everything's ok because of the drive time and all sensors are not out of spec - resets any condition it may have to think about.

So if the Check Engine light is NOT on, the test seems to have failed because of cold temps - doesn't always set a MIL (Malfunction Indicator Light)..

So since everything else - including the Hydrocarbon (HC) Test seems ok, you might just have a plugged filter - usually air filter or even a plugged PCV valve - you'd see oil leaking out of the motor because of compression and poor ventilation of the crankcase caused by it. Poor grade petrol fueling-up more than once can put your engine out of whack faster than driving with low oil levels and cardboard stopping up the airflow thru the radiator.

This is a Zetec motor, they are quite old in both age and their emissions - sensors and hardware are from that era - also showing this age too so this changes efficiency.

If you have time check the EGR valve - these can plug as well. Can also cause some performance issues too.

But if it "burns oil" when you shift or start out - this immediately puts you in "fail" because burning oil blow-by is partly the reasons for this test they do. The higher CO output and the soot from it - the oil smoke - is why they are cracking down. That's a new rings even cylinder valve head work that will need to be looked into.