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Discussion Starter #1
I am having a real nightmare with my 147 1.6 tspark, firstly lambda sensor 2 bank 1 wasnt giving out a voltage, i traced it back to a bad contact in the ecu, new ecu installed problem fixed... Now i have driven the car for 220 miles without a problem until yesturday when all three lambda sensors decided to stop working correctly!!!!!
Two of the sensors bank1 sensor1 and bank 2 sensor 1 are not giving me a voltage once the car heats up!! bank 1 sensor 2 is sitting at an unusal 08 v rich nearly all the time but some times the voltage dissapears totally on it as well. I am at my witts end now with this one, surely all three lambdas havnt gone at once????. heres what i have tryed so far

changed the maf no difference
cleaned all lambda connections including ecu connections with contact cleaner
cleaned all the cars earthing points in the engine bay
replaced the engine loom with a known good one.

The car has cost me a small fortune on time and bits and if this isnt a simple fix it will be up for spares/ repairs. Any help or other ideas greatfully received...
 

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Discussion Starter #3
Thanks for the idea have done that and also ran a seperate earth to the exhaust just incase.... no idea what the problem is, starting to think maybe knackered cat?
 

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Thanks for the idea have done that and also ran a seperate earth to the exhaust just incase.... no idea what the problem is, starting to think maybe knackered cat?
no continuity of lambdas >>> electrical

if your cat is shot you should see post cat graph with wavy line instaed of a flat line of mid may of graph
 

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Discussion Starter #7
nope the engine redlines ok, idle is lumpy however. should they not still not switch rich to lean the same as bank 2 s1?
 

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Discussion Starter #10
yea mine are not switching in cruise conditions!!!. Its a weird fault with this one because i have been monitoring all three lambda voltages with the computer whilst driving to work and one day my back lambda on bank2 s1 wasnt creating a voltage and the very next day it was?, and s1 on precat does nearly nothing, s2 on precat sits at about 0.8v and then the voltage can dissapear from it too sometimes. Thinking of trying some new sensors on the precats it is however and expensive mistake if they dont cure it at £90 each...
 

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bank 1 sensor 1 is left hand pre cat
bank2 sensor 1 is right ....... these two are classed as sensing

sensor 2 is post cat which is termed diagnosing that tells if ya cat is stuffed so to speak
 
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remove the pre-cat lambda [ 22mm spanner required ] & shine a torch in the hole, look for honeycomb internals, if none there the pre-cat is empty
 

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What are the emmisions?? have u had them checked. You may find its something simple like a hole in the exhaust and the lamdas are trying to compensate by running richer
 

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Discussion Starter #16
Bank 1 s1 and bank1 s2 are the two sensors at the precat at the manifold, Bank 2 s1 is the one in the actual cat. I have been monitoring all three sensors for two days now and bank2 s1 has started working normally switching from rich to lean every second or so which is good news. The two sensors at the precats are hit or miss they have worked properly sometimes and then the voltage dissapears!!!! I am going to try new bosch sensors to rule my ones out..... the emissions are normal as i have checked them... and the cat internals are all there and dont appear to be blocked..
 

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Bank 1 s1 and bank1 s2 are the two sensors at the precat at the manifold, Bank 2 s1 is the one in the actual cat. I have been monitoring all three sensors for two days now and bank2 s1 has started working normally switching from rich to lean every second or so which is good news. The two sensors at the precats are hit or miss they have worked properly sometimes and then the voltage dissapears!!!! I am going to try new bosch sensors to rule my ones out..... the emissions are normal as i have checked them... and the cat internals are all there and dont appear to be blocked..
think your confused which ones are what bank 1 s1 and bank 2 s1 are pre cat and switch s2 is post cat which is diagnosing and shouldnt switch if its switching there must be problem with cat either manifold cat or silenced cat:thumbs:

can some one else clarify please
 

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Discussion Starter #18
Bank 1 s1 and bank 1 s2 are the two sensors on the precats at the manifold are they not? and then bank 2 s1 is on the middle cat???. Are you saying one of the sensors on the precat isnt meant to switch from rich to lean? and stay constant?, I assumed it would have had to be switching to deliver equal amounts of fuel to each of the four cylinders which is why i thought there was two in the first place one precat sensor for two cylinders???
 

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Bank 1 s1 and bank 1 s2 are the two sensors on the precats at the manifold are they not? and then bank 2 s1 is on the middle cat???. Are you saying one of the sensors on the precat isnt meant to switch from rich to lean? and stay constant?, I assumed it would have had to be switching to deliver equal amounts of fuel to each of the four cylinders which is why i thought there was two in the first place one precat sensor for two cylinders???
see post 13:thumbs: disconnect them and see what one throws fault code to work it out

i am saying pre cats switch post doesnt:thumbs:

remember voltage is small off these any any poor connections can and will throw it all out
 

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Hi mattys147, did you manage to resolve this? I'm having a similar fault with intermittant lambda readings, can't find a problem with the loom or earthing points, and lambdas read normal until you put the car under load, reluctant to splash out £180 on new sensors to find its something else dodgy.
 
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