1998 AGU Emmission issues

[manwithtool]

I have an AGU in my T4 van. and it's emissions failed the MOT. I don't have any engine warnign lights set up but I do have an code reading port. I'm hoping it a temp sensor. I replaced this about 2 years ago and from memory it's a black 4 pin sensor that happened to fix the temp gauge as well. But can someone confirm this 4 pin does the ECU engine temp or is there another one somewhere else.
Thanks

 

[Vex182]

What is the actual fault with the emissions?

 

[manwithtool]

I didn't get the read out... bu I think it was Hydrocarbons and Co2, tickover and higher up. I has passed the emmission for last two years so don't think it has anything to do with the install !
I know when I had the standard 2.0 petrol I had to change the blue 2 pin temp sensor every two years. Figured I might have the same problem but not sure which sensor tells the ECU what temp is. Figured this was an easy starting point. I still need to download any error codes...which is probably what I should do before posting on here.

 

[<tuffty/>]

Faulty temp sensor will potentially make the ECU think its still in cold start/warmup so will run richer... the newer sensor is green and sits in the coolant housing on the end of the head... this should be a 4pin one and will do temps for both the ECU and the dash...

Plugging in with VCDS and looking at block 001 in the engine module will tell you what temp the ECU is seeing...

You can check this against the dash and/or by looking in the instruments module (assuming its supported by your T4) and checking what the other sensor is saying... its not unusual for them to be a few degrees different but for the ECU to be stuck in cold start the ECU would need to see less than 70 odd degrees typically...

Seeing 90 on the dash and 70 odd (for example) on VCDS normally means a fault in the sensor the ECU is using

<tuffty/>

 

[manwithtool]

Thanks Tufty...Perfect answer

 

[manwithtool]

Well I downloaded some codes and all I got was an error code which apparently is running Rich. I thought the code was 0506 or 0560..
I wrote the code down but left it at home...any thoughts. ? When warm and at tickover it seems to have a "cough" every 5 seconds or so.. like a missfire.

 

[<tuffty/>]

Exact code (preferably with VCDS) would be useful

00560 seems to be related to an EGR fault which is a TDi issue so can't imagine its that

00506 appears to be related to idle control which is plausble on an AGU

Neither suggest they are a code relating to running rich...

Those codes are not listed on the VCDS wiki...
http://wiki.ross-tech.com/wiki/index.php/Category:Fault_Codes

VCDS will have them as a reference though, just not made it onto the wiki

<tuffty/>