replaced breather pipe, now engine management light is on?

[gttjames]

Hi guys, following on from this post...

http://www.golfgtiforum.co.uk/index.php?topic=207848.msg1930451#msg1930451

I replaced the pipe with a OE pipe as needed it asap so got it from main dealer as was in stock, done about 30 miles in it over a couple of journeys, and engine management light has just come on?

Seems strange as didnt have a light on with a split pipe, but now iv replaced it, its come on?

[richw911]

Fault codes? Could be coincidence 

[gttjames]

Well it had mot and service yesterday - i did a full service on it and replaced everything so i know its all been done, cant allways trust previous service book, used all genuine parts and put 2 rear coil springs on it (nsr coil spring was missing a coil at bottom so did both) - total price of parts was just under £70 - well cheap compared to parts for my megane r26 lol! They mot and she went straight through.

Popped into seat next to my workshop and they kindly read the car for me and turned the light off - there diagnostic machine said it was running rich and was most likely to be a o2 sensor or maybe and temperature sensor. Going to try a o2 sensor you reckon?

After resseting light it was running fine, but when it gets hot if you pull up at a junction to idle itl just be really up and down

[littco]

If you had a split pipe then more air than the mad reads gies into the engine, the O2 reads this as a lean condition and will adjust the fuel trims to add more fuel to get the O2 readings back to correct settings. Then you replace the the split pipe and the trims are still at the old settings but now you have the added fuel and lower air flow. Light comes on for an over fuel as trims are exceeded. Resetting the ecu and clearing the faults will set it all back to standard so clearing fault. However throttle will also be  so a throttle adaptation will help.