My mk1 octy is still new to me, I keep getting O2 sensor fault, I have just replaced the probe but fault will still appear daily, under my bonnet there is a Forge valve fitted at the front of the engine it's not a dump valve as it does not make that kinda noise, however it does whistle loader as I go faster? My main question is, could this mod create my EML if my car has not been remapped? I also have receipts for blueflame down pipe and cat and cat back system!

It also had "briskoda" number plates on it previous owner must of been a member?

There are 2 02 sensors i.e pre cat & post cat.

Sounds like the previous owner fitted a Forge diverter valve to the cold side of the engine. It certainly shouldn't be whistling at all. The whistling is probably the turbo spooling up.

If you have a 02 sensor code coming up then that's where the problem is.

Edited 9 November, 201114 yr by pauldazzle

also sounds like someone has re directed your DV to the front of the car. Is there a DV on top of your turbo intake pipe ( the pipe the comes off of the airbox and goes down the back of the engine)or is a long pipe that trails to the front where this forge valve is.

Did you do it yourself, or did you buy the car like it? If you bought it like that.... I remember you get an EML if you have been fidling with the secondary air pump and what not.

This is how the car came I've not touched it YET!

The valve if defo fitted to pipe off of the throttle body.

It appears there is a standard OEM valve fitted off the back air intake pipe, I'm some what confused.com to weather valve is actually doing me any favours? ( at the front )

Back to my O2 sensor fault it was a code for pre cat bank one sensor one! I replaced it for new, but didn't make any difference, could the valve cause air / vacuum issues creating false oxygen readings on the lambda probe?

Ps the pipe at the back right (I think off the turbo ) has a short hose about 3" with a forge blanking plug! I'm assuming for no recirculation?

Ok I've just read up on DV relocation and can see the benefits from the cold intake, if this is causing my EML O2 fault, I'm guessing I'm going to have to map it out with a custom code! If all this work has been done on my car surly this would cause some kind of issue?

what is the specific code for the lambda mate is it saying out of specification or is it saying heating circuit open or short circuit?

17511 - Oxygen (Lambda) Sensor Heating; B1 S1: Performance too Low

Did you clear all codes after you replaced the sensor? Otherwise the code will still be there even if the sensor is working. Also check the wiring loom to the sensor.

No idea why it would have two DV's but I would remove one of them and blank the pipe off so you're just running with one. Presumably they have fitted vac hoses into the top of both DV's so they open properly. Rob's site has got some good pictures of how the relocated DV should be set up: http://www.pimpmyskoda.co.uk/V2Images/ModsEngine/DV%20Relocation.htm

Ok that code is to do with the heating circuit nothing to do with the dumpvalves or emmisions at all really. start by checking all the fuses in the fuse box and test EVERY one that is to do with the engine management first. check with a multimeter that there is 12V across the 2 heating wires to the lambda (both white if I remember right)with the ign on and cold engine.

Is where I would start anyway .

I'd sort those valves out as well, althought they don't sound like your problem, they do sound like a bodge job of sorts

I have cleared the code every time, I have a tool to do so curtasey of eBay!

I'm loving the advise checking fuses will be next, learning as I go!

I've been in the motor trade since 96 and currently work for Volvo (sorry to sware on here) I have also spent many years at VW and owned a mk3 golf gti, this is my first turbo car, so learning about things like this interests me a great deal!

Ps since I started this post, I have found a redundant vacuum solenoid to a boost gauge that no longer exists in the car! I have cut off and blanked off the pipe incase I had a leak from the solenoid!?

Cars gone back into garage today to look at the new O2 sensor they fitted! Update tomorrow to see if code 17511 has gone once and for all!

Garage has admitted to replacing bank 2 ( the wrong sensor) hopefully my stress will be over once they replace the correct sensor!

My ongoing issue finally came to end today, here is the short version,

The previous owner had fitted exhaust system including a sports cat, however bolted pre cat probe into the post cat hole and vice verser! They were wired correctly BUT because I had a B1 S1 heating element fault the wrong probe was changed!

Ok so 2 new probes fitted (correctly) and hey presto, no more 17511

I must admit I'm very supprised my car didn't through a fit with messed up air fuel readings with probes in incorrect ports!