2003 Vauxhall Astra loss of power above 80mph eml on

If the EML is on then there's a fault logged/stored.
you need it scanned.

It's a safety device to stop the engine blowing up . Only joking , the possibilities on a car of that age / mileage are endless . As suggested by another poster , get it scanned rather than guess

ok thanks for the response. Scanned it came up O2 Sensor heater Circuit Bank 1 Sensor 2.
Ive erased the code just have a service light up.
Hoping this is an easy fix hoping its not the Cat havent yet had the opportunity to see if its cured well not cured but see if it will allow the car to accelerate above 80mph.

A partially blocked cat / exhaust is a possibility if replacing o2 sensor doesn't cure it .

ok wont rev above 4000rpm checked the air filter alls fine with that?? I really have no idea after that how can I check for an exhaust blockage?

theres quiet a bit of oil around the carb though

You dont have a carb , it''s a throttle body .Check engine is breathing o.k through hose / PCV valve .If not will build up back pressure a possible cause oft the oil you are seeing .

lol ok shows i dont have a clue.
Anyway i can check the hose pcv valve and where is this?

Has it a cambelt? If so check cam timing and cam sensor. If timing out or sensor failed vauxhalls will not rev past 4000 rpm stationary. Try disconnect cam sensor and rev up