Hi everyone,

I own a Skoda Felicia Fun pickup and I’m having a persistent issue getting it through the MOT emissions test. It also runs with low revs on a cold start, but once the engine warms up, it runs fine. I’ve already taken it to two different mechanics and spent hundreds, but the issue is still unresolved and emissions sky high

What’s Been Done So Far:

First Mechanic:

• Lambda sensor replaced

• Throttle body swapped with one from an identical Felicia Fun (no change)

• Temperature switches replaced

• Air leak found and repaired

• Smoke test done to check for further vacuum/air leaks (none found)

Second Mechanic:

• Another smoke test done – no new leaks found

• Distributor cap and rotor arm cleaned/replaced

• Throttle body cleaned

• Evaporator valve replaced

Suggestions/Possible Causes (from mechanics):

• Possibly injector-related

• Possible ECU issue

• Vehicle had been sitting for 2 years before I bought it

Has anyone else had similar issues with the Felicia Fun or the 1.6 engine? I’d really appreciate any insights or suggestions on where to look next.

Thanks in advance!

1 hour ago, JonjoWood said:

I’d really appreciate any insights or suggestions on where to look next.

Given the liberal use of the parts cannon, I'd suggest an Italian tune up next, preferably with a reliable mate in a faster car following you to report on any exhaust smoke (colour and density).

Hi, welcome.

There are lots of similar posts and threads on here with problems (from vehicle not being used) that you can look at - most important are brakes!, steering and suspension (all three include tyres), safety electrics (lights, horn, wipers, blower, etc.) number plates (see and be seen) then perhaps engine and transmission.

Is the engine original ("Petrol 1.6  litre VW Engine AEE MPI (Magneti Multi Point Injection 1598cc, 8v, SOHC) 55 KW 75 PS 5 Speed Manual Gearbox")?

Your possibly causes look, er, possible, add in (indirectly perhaps) if old petrol was left in (and perhaps even E10 wot it don't want, keep filling the petrol tank with higher octane E5 with added cleaning package as per pdf attached below, and Sainsbury's 97 not on list). And then get the engine fully warmed, for a reasonable time then drive it at sensibly higher revs, say 4,000, not high speeds, for a good number of miles 20-50 miles. If that proves an improvement repeat,

Have you changed the engine air filter and cleaned the air box and tubing, changed or at least checked the spark plugs, changed the engine oil &filter (fuel filter?)? For Italian tune-up you can start with fuel filter(?), engine air filter and box and tubing.

Careful of new parts like lambda sensor, that has to be correct one rather than generic and things like new modern made rotor arms (and other parts) can be ****-poor quality, if the old parts are OK hold on to them just in case they're better worn than the modern made parts new. If the rotor arm wasn't bad I'm not sure why the second mechanic changed it as that usually relates to misfires and starting.

You could check the ECU to make sure it's not damp/wet/crudded-up.

HTH. Let us know how you get on.

petrol.pdf

5 hours ago, JonjoWood said:

Possibly injector-related

Can be measured in few minutes with a manometer.

5 hours ago, JonjoWood said:

Distributor cap and rotor arm cleaned/replaced

Has a 1.6 Felicia year 1999 (with ECU) these?

NO need for E10, E5 works perfect.

Spark plugs checked?

I don't suppose you got the emission figures (maybe on a print out) from the exhaust gas testing machine.

Might help narrow it down.

On 23/08/2025 at 11:48, JonjoWood said:

Temperature switches replaced

What does this mean? Switch on the radiator? Coolant temp sensor? Intake air temperature sensor?

I didn't see mention of the fuel filter replacement. I'd try that, especially if the car didn't run for a long time.

Another thing would be check for exhaust leaks - Felicia has oxygen sensor after the flex pipe, a leak there could throw the readings off. (This happened on my car with a similar VW engine)

Did any of the mechanics do proper diagnostic reading, i.e. check the values instead just the fault codes?

On 02/09/2025 at 10:37, Papez said:

What does this mean? Switch on the radiator? Coolant temp sensor? Intake air temperature sensor?

I didn't see mention of the fuel filter replacement. I'd try that, especially if the car didn't run for a long time.

Another thing would be check for exhaust leaks - Felicia has oxygen sensor after the flex pipe, a leak there could throw the readings off. (This happened on my car with a similar VW engine)

Did any of the mechanics do proper diagnostic reading, i.e. check the values instead just the fault codes?

Also if I may add, using some real time data from lambda sensors could reveal more, although I think given the age, and/or possibly oil consumption, the CAT could be poisoned.

On 23/08/2025 at 12:48, JonjoWood said:

1. Possibly injector-related

2. Possible ECU issue

A dirty trick to pass, especially if the vehicle shows high HC or CO content, is to force it to run lean, very lean, by installing an external fuel pressure regulator just to pass MOT. Then you can remove, but beware, for legal reasons you never heard it from me.

Remind my the dirty trick of old time taxi drives with excessive diesel emissions, before the MOT few gasoline in the tank to be mixed with diesel and for a while to give lower emission numbers.