Volvo Owners Club Forum - Lambda light on but cars fine, help!!

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- - Lambda light on but cars fine, help!! (https://www.volvoforums.org.uk/showthread.php?t=292752)

Quote:

Originally Posted by canis (Post 2504365)

I'm sorry if I've given the wrong impression! I'm nowhere near knowledgeable on this subject - I only know what i've read, desperately trying to scrape my cars through their MOTs each year like yourself.

Are you absolutely certain the cat was changed for a new one? It's doubtful it would fail so quickly, unless it was burnt out by some other problem (unburnt fuel?) prematurely. They're supposed to last for years.

I'm sure there are forum users who know more about this than me. I would've thought they'd have something to say on this thread by now, I sure hope they do.

I would hazard that the lambda sensor and cat have similar life expectancy. They work by chemical reaction, and don't last forever, so if it's on it's original sensor it's entirely likely it's at the end of it's life. They don't entirely stop working, they emit (or affect in some way) a pulse of electricity according to gases present, but as they age the range between high and low becomes thinner. I've often wondered if their life could be extended crudely by amplifying this effect, in a smiliar way to how LAN repeaters extend range, but i've never put any experiments into action. After my kitten relieved itself on my ancient oscillloscope, such experiments are rendered beyond my technology. I went through all this with my old Sierra.

As in the previous post, the best bet is to get codes read if you can. Otherwise, it's down to buying sensors and replacing them until the problem is fixed. Which sucks, but it's the only option really available to a home mechanic stabbing in the dark.

Again, sorry I can't help more.

No problem Haha. Yeah the cat was changed by a garage when it failed and by myself with a brand new part last year. Saxo only gives catalyst inefficiency code when I rear it with a bluetooth reader and torque lite app. Tesco 99 took the light off last time so got half a tank in there now and going for a decent drive to Costco this evening. Mot runs out on the 20th. All is well. Thanks!

Quote:

Originally Posted by canis (Post 2504364)

Ah, interesting. Not many of the phase 1 models still around, even mine is parked on the garden, but there's a lot to like about them and in my opinion they are in many ways superior to the other marques.

There are many things which can cause over-fuelling. The obvious answer is to get the OBD codes read, although in this regard the phase 1 is a bit of a nuisance - it only partially adheres to OBD standards. And you need the technology. A PC can do it, just barely, although my attempts were rather hit-n-miss.

Off the top of my head, I would suspect the lambda sensor, the MAP and MAF sensors also. Without accurate diagnosis you'll be guessing.

I wish I could help more.

I can't actually read any codes from the car. with some software I can reset things like service lights , air bags and that kind of stuff but I can't access any engine codes. Reading about on here it seems that is normal although the garage thought it could be an Issue with my ecu?

I have a spare map and lambda sensor I took off the car when I had issues before but turned out not to be the issues so could try these again and see.

Quote:

Originally Posted by KBB (Post 2504369)

Can you post the results of all the gas analysis readings ie:

CO %
O2 %
CO2 %
HC ppm
Lambda Numeric Value

There should be Two sets of values one for idle and one for Fast Idle (part load)

I don't know the values I'm afraid but the co was high and the lambda was low the others where fine.

while working on the LPG conversion I removed the oil catch can thing below the intake manifold as this was blocked when I got the car. Upon removing it there was a lot of milky oil drain out and the thing was full again, this had also caused some to go up into the manifold and therefore get burnt which I feel could cause or at least contribute to the problem. What would cause this to block up, it seems its for removing moisture or condensation that collects in the oil. the rest of my oil is fine I have no issue with a head gasket to milky oil on the filler.

so the oil thing hasn't solved it. I changed the lambda sensor because when I did the LPG conversion I wasn't getting a signal from it so put the old one back on which worked and I got a signal from it but the light is still on in the car!? what else could I try?

I think, if i remember right, the light won't go off in this situation without using software to clear the error code and switch the light off. As a desperate measure, you could try disconnecting the battery overnight. (Radio code!)

Quote:

Originally Posted by canis (Post 2505267)

I disconnected the battery for about 20 mins so maybe that's not enough. I'll plug in my computer and see if they're are any codes on that then.