Lambda oxygen sensors

[Ginger Teddy]

Hi folks, I have the EML come on occasionally and I plug in the reader and it always says P0420 (cat efficiency below threshold bank 1). I usually switch light off and continue to use car as normal as it doesn`t run any different unless the Mot is looming then I put a bottle of cataclean in and give it an italian tune up. It gets through the Mot ( not due until september) although it did struggle on the emissions on the last one.I know it`s several months away before the next Mot but I have been reading up on these Lambda oxygen sensors and how they can give a false reading if faulty. I have had the car 10years and it came with a lot of paperwork etc, nothing to say they have been replaced, so I would presume the two sensors and the cat are the original`s. I was thinking of replacing said sensors before we go down the replacement cat road. I see on ebay ( 165076814795 ) RTG Automotive replacements the same sensor fits pre cat and post cat.Can someone in the know confirm this please. I always think that if you buy cheap you buy twice so would be looking for a decent replacement for fitment. I have the 2004 1.8 turbo tourer. Has anyone replaced these sensors and has it made any difference to EML light showing itself occasionally or has it still made you question the state of the cat? As always any information/advice always appreciated, regards Paul

[trikey]

Have a check of the wiring that comes from the sensors as this can chafe through on the exhaust shield, it might be a tiny break in the wires coating that's causing your issue.

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[Ginger Teddy]

Hiya Andy, I will check the wiring like you suggest as yes it maybe the case of something that simple has happened . It makes me think of the brake sensor light showing up on dash only last week and having a rear seized brake caliper replaced along with discs and pads in January and only done 100 miles since, I found the rear brake pad sensor wiring bent and hanging on only by 2 of the exposed wires and had been chafing on the inside of the rear wheel.So it hadn`t been tucked far enough out of the way by the so called professionals when put back. So after parting with £596 to these people I had to wriggle under car to replace said sensor, luckily it was the easier of the two being at the rear. Just got to wait for a drier day to look at this problem. Thanks for advice, regards Paul

[Ginger Teddy]

Hi folks just another quick question about the electrical connectors on replacement Lambda sensors . Many say direct fit showing a square type of connector, as I will be replacing both sensors would that be correct as when I get the car jacked up it will be to replace and not just to have a look as not the easiest job. Why I ask is the brake pad wear rear sensor I changed recently had a round connector and I don`t fancy getting that far and finding electrical connector is wrong, again advice much appreciated, regards Paul

[Jdwoodhou]

I recommend you buy an OEM sensor. I bought cheaper ones and they failed after 200 miles. The front is likely to fail first so try just doing that one. Plus Gas is great for loosening the thread, leave overnight. Final tip, make sure the block end of the connector fits the lead on your block before removing the old one as some are keyed differently

[Ginger Teddy]

Hi, I have been able to get 2 OEM sensors as I don`t want to be replacing again in short space of time. I note you say that the front one is likely to fail first and that was my thought mainly as it has the easiest access. Yeah will check connections just to make sure we don`t do the hard work and find connection is different,what a school boy error that would be lol. Weather supposed to be decent this coming week so will get that done. Advice as always is appreciated, regards Paul

[rab60bit]

Originally Posted by Ginger Teddy

Hi, I have been able to get 2 OEM sensors as I don`t want to be replacing again in short space of time. I note you say that the front one is likely to fail first and that was my thought mainly as it has the easiest access. Yeah will check connections just to make sure we don`t do the hard work and find connection is different,what a school boy error that would be lol. Weather supposed to be decent this coming week so will get that done. Advice as always is appreciated, regards Paul

Just replaced a KV6 Lambda post cat. sensor supplied by DMGRS, female end connector fitted fine - didn't fix my problem but hey you can't have everything when you're a MGR owner.
Tip, remove the whole connector from it's bracket/clip first and then split the male/female halves of the connector (just simple press in and pull sort of action, what you press becomes evident once once the assembly is free of it's bracket.; the assembly is held in place by a clip, just slip an electrical screwdriver blade behind the clip and the whole lot will slide off the bracket.

[Ginger Teddy]

Hi , thanks for the tip regarding the connectors it is noted. I am hoping by changing both it may make a difference but the car is 19 years old and I am pretty sure the cat is the original and nothing lasts forever , but keeping fingers crossed. Saying that I had a 1992 (1993 run out model) Ford sierra sapphire and it had a cat and had that car for 23years with no issues regarding emissions .Probably just lucky with that one, regards Paul