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 Posted: Wed Sep 20, 2017 8:12 pm |
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Joined: May 05, 2011
Posts: 23
Trade Rating: 0
Location: England
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Hi Guys,
So, about 10 years ago, I bought a heavily modified for the track 206cc 2.0.
It required work, but it has worked great for a long time. It's always a pleasant surprise when I find something new in it.
It has passed its MOT without problem for the past 10 years.
Now, recently, a CAT emissions fault came up. I investigated to see whether or not I needed a new CAT or a new O2 sensor.
Well, PP2000 shows that the Downstream Sensor is always at 0v. I thought this must be the problem and bought 2 new sensors (in hopes of replacing both together).
Before that though, I tested the downstream sensor and it seems to work perfeectly. I swapped the upstream and downstream sensors and I still get 0v oon the downstream in pp2000.
I spent the entire day today tracing the wiring and testing to the ECU connector - the downstream O2 signal is live and present right into the ECU connector.
The ECU just doesn't detect it!
It has really got me scratching my noggin...
So, it got me thinking:
1. Either the ECU is faulty, being unable to detect the second O2 sensor, even though everything else is fine.
2. The people who built the track car purposely reprogrammed the ECU to disable the downstream sensor for more power / prevent codes caused by high flow exhausts etc.
Question: Is it likely to be #2 or am I diluding myself? Is disabling the downstreamsensor done often as a mod? Does it affect MOT emissions tests? (if not then this would explain why the car has passed with flying colours for the past 10 years).
Thanks for any insight!
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Posted: Fri Sep 22, 2017 1:36 am |
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Joined: Feb 07, 2010
Posts: 620
Trade Rating: 0
Location: Malaysia
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| Zash wrote: |
Hi Guys,
So, about 10 years ago, I bought a heavily modified for the track 206cc 2.0.
It required work, but it has worked great for a long time. It's always a pleasant surprise when I find something new in it.
It has passed its MOT without problem for the past 10 years.
Now, recently, a CAT emissions fault came up. I investigated to see whether or not I needed a new CAT or a new O2 sensor.
Well, PP2000 shows that the Downstream Sensor is always at 0v. I thought this must be the problem and bought 2 new sensors (in hopes of replacing both together).
Before that though, I tested the downstream sensor and it seems to work perfeectly. I swapped the upstream and downstream sensors and I still get 0v oon the downstream in pp2000.
I spent the entire day today tracing the wiring and testing to the ECU connector - the downstream O2 signal is live and present right into the ECU connector.
The ECU just doesn't detect it!
It has really got me scratching my noggin...
So, it got me thinking:
1. Either the ECU is faulty, being unable to detect the second O2 sensor, even though everything else is fine.
2. The people who built the track car purposely reprogrammed the ECU to disable the downstream sensor for more power / prevent codes caused by high flow exhausts etc.
Question: Is it likely to be #2 or am I diluding myself? Is disabling the downstreamsensor done often as a mod? Does it affect MOT emissions tests? (if not then this would explain why the car has passed with flying colours for the past 10 years).
Thanks for any insight! |
Hey mate last time i swap the ecu from early model 206 gti, i found out that some ecu wont detect the 2nd sensor.. i think the one on your car now is from the older model 206 .. if not mistaken early model dint have 2nd o2
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Posted: Fri Sep 22, 2017 5:49 pm |
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Joined: Feb 07, 2010
Posts: 2716
Trade Rating: +6
Location: UK
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I was going to say that! Edward could confirm on his Gti i expect.
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Posted: Fri Sep 22, 2017 8:25 pm |
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Joined: May 05, 2011
Posts: 23
Trade Rating: 0
Location: England
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Hey, that's cool. So what you're saying is that someone might have taken out the original ECU and replaced it with an older one.
And this is the reason why the second o2 signal is detected all the way into the head of the ECU connector but not the ECU itself?
Huh 
How would I confirm this?
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Posted: Sat Sep 23, 2017 8:01 am |
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Joined: Feb 07, 2010
Posts: 2716
Trade Rating: +6
Location: UK
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Thinking about it though you wouldn't have the connector on the loom. What year car is it?
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Posted: Sun Sep 24, 2017 9:53 am |
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Joined: Feb 07, 2010
Posts: 620
Trade Rating: 0
Location: Malaysia
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| Zash wrote: |
Hey, that's cool. So what you're saying is that someone might have taken out the original ECU and replaced it with an older one.
And this is the reason why the second o2 signal is detected all the way into the head of the ECU connector but not the ECU itself?
Huh
How would I confirm this? |
yes that s true..but i wont be having any problem..check my pmed
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