Engine exhaust emissions - MOT failure

[charlier6790]

Help! With only 57,000 miles (and having recently had a 60,000-mile service at a Jaguar specialist) my car has failed its MOT because the CO and HC emissions are off the scale. My local garage thinks it's the two upper Lambda sensors (the ones nearest the engine) and say that they cost nearly £400 each from Jaguar. That's almost £800 plus labour. Does anyone know if pattern or second-hand parts are an option - and where I might obtain them, please?

Sorry if I've posted this in the wrong area. I wasn't sure if emissions and Lambda sensors fell under electrical, fuel, exhaust - or something else!

[E_PITT]

If you live anywhere near Coventry you could do far worse than give Chris Forbes a call. 01676 541917. I had the same problem with my XJ8 and Chris seems to be able to source good used parts. Worth giving him a call just to talk it through. Best of luck. Ed

[ptjs1]

charlier6790,

You haven't told us which engine and year car you've got (it's much easier if you add it into your signature). There are differences in the sensors used in early and late engines.

First of all, a decent garage can definitely tell you if the output signals from the sensors are corrct or not. It's an expensive unnecessary cost if it's not really the sensors!

However, either way, you can pick up new original equipment sensors at a fraction of that £400 price. Most Jaguars of early to late 90s use NTK sensors. As an example late XJS sensors are £250 in a Jaguar box but the exact same NTK sensor can be found for about £70.

If you've got a 4 litre then you can get the correct top sensor for about £99. Try www.gendan.co.uk or www.britishcarparts.co.uk

You can also get universal pattern sensors even cheaper but my preference is to go for the original manufacturer ones. I also wouldn't fit seond-hand sensors as they really need to be treated as consumable items.

Good luck

Paul

[joejag308]

charlier6790........before panicking i would have the diagnostic test done to make sure its the sensors......only thinking it could be the sensors is not correct without having the scan done......Joe

[charlier6790]

Many thanks to you all for the helpful advice - it's much appreciated.

I've now had the car scanned and it appears that the fault is linked to the upper L/H Lambda/oxygen sensor.

The scan result was "P1647 heated upstream oxygen sensor control malfunction bank 2 option shorted."

I'm sure that means more to you than it does to me!

Sorry not to have included full vehicle details - the car's a 1999 4-lire Sovereign - VIN Number 875893.

[joejag308]

charlier I submitted your problem to Dave Marks and his reply is.......

Hi, Joe

it is possible that the l/h upper oxygen sensor heater element has failed.

he will need to disconnect the sensor and check the continuity of the two wire to the heater in the sensor - the wire colours are either Purple/slate and white/green, or purple/blue and white/green - the former I think.

These are the wire colours to the main harness, so those leading to the sensor may well be different.

If they read open circuit, the sensor is definitely u/s, if they are OK, it may be the sensor or it may be something else.

Hope this helps, you will no doubt have noted my auto reply, so answers may be delayed from now on

David...............
As you can see this diagnosing is extra work for the experts it really is beyond their remit......so another system of contact has been set up.
Joe

[charlier6790]

Hi Joe

Thanks for such a speedy response.

I'm now arranging to take the car to David Marks so he can check-out whether it's the sensor, the heater element or something else.

I'm really grateful for all the help and support from you and everyone else.