Talk Morgan Forums Morgan Sports Cars Classic Morgans (pre-CX) 2.0L Duratec Lambda Sensor

Judging by fumes, could even be a loose or poorly seated exhaust clamp? Mine was discovered a bit loose in the past.

I would say yes. A leaking exhaust can cause a (wrong) error message from a failing oxygen sensor.

I just changed a lambda sensor on my Rover V8. It was solid and I couldn’t budge it with an open ender and stopped trying before damaging the hex nut part. Plenty of Plusgas used.Fault was open heater circuit in downstream sensor. OBD unit identified it. Tested both L and R. Twin exhaust system. R one was the faulty one. Ordered replacement from Rimmer Bros. Got my MOT garage to replace it due to my failure. They had to use a blowtorch to release it. They are notorious for being b******s to get out. Now ok. Car has done 73k miles so not bad life.
Same sensor use pre and post cat. I got the pre-cat one out easily to look for ID but couldn’t track a new one down until finding the ID on the Gems system manual.

Hello

I have to change a lambda sensor in amount of the cathalisathor on the roadster.
Apparently there are 2 sensors by each exhaust.

The check engine is constantly yellow after a restart

I found on my S1 Roadster that cheap supermarket fuel fouled the sensor. You could try running with E5 branded fuel & use a cat claener to see if it clears.

If there's no damage apparent to the wiring or connector remove them and clean them, I use aerosol cat cleaner and toothbrush or similar! Yep, one in front of each cat and one behind. If you have on OBD 2 reader it might tell you which one it is, certainly you'll get the side it's on. Buy yourself a proper lambda sensor spanner as the sensors are easily damaged, spanner not expensive on the Bay! Lambda sensors are! Use penetrating oil first and leave overnight. If it's still to tight use some heat at the threads on the exhaust itself and when hot try again it should then undo. watch the wiring when applying heat and obviously any other issues that could cause damage or fire risks! Lambda sensors are colour coded and the front and rear are different. It is possible that one has failed but usually it's dirt or wiring issues on these low milage cars. And they sit right in the wheel arches!

If there's no damage apparent to the wiring or connector remove them and clean them, I use aerosol cat cleaner and toothbrush or similar! Yep, one in front of each cat and one behind. If you have on OBD 2 reader it might tell you which one it is, certainly you'll get the side it's on. Buy yourself a proper lambda sensor spanner as the sensors are easily damaged, spanner not expensive on the Bay! Lambda sensors are! Use penetrating oil first and leave overnight. If it's still to tight use some heat at the threads on the exhaust itself and when hot try again it should then undo. watch the wiring when applying heat and obviously any other issues that could cause damage or fire risks! Lambda sensors are colour coded and the front and rear are different. It is possible that one has failed but usually it's dirt or wiring issues on these low milage cars. And they sit right in the wheel arches!

Forgot to say! Supermarket fuel is cheap because it doesn't have the additives the premium fuels have, part of which are cleaners!
Like regular oil changes are the cheapest repair you can carry out, so too is fuel quality. just use the 98 RON premium fuels which burn cleaner and have all additives to clean and lubricate the fuel/combustion areas of the engine. You will get more miles to the gallon and more smiles to the mile as well! When you look at cost per mile it will be almost non existent!

It's worth remembering that supermarket fuel has to meet the same super strict British standards as all other fuels, these standards are extremely rigorous so people should not be put off by buying fuel from a supermarket fuel station.

In my experience what kills lambda sensors in short order is lots of cold starts, and stop start driving. The worst case scenario being starting an engine, moving a car a short distance then switching it off so never giving it enough time to fully warm up. Just like a spark plug, lambda sensors are self cleaning, that is you need to get them hot to perform their self cleaning function, if they never get to the critical self cleaning temperature eventually all those super rich condition cold starts will poison the lambda sensor and a error code will follow.

The OP's Morgan has only done 2,000 miles, on the face of it you'd think the lambda sensor would last a lot longer than that, but it's actually the low mileage that points to why it failed. I suspect the car sat in a dealer’s showroom for a long time, and the dealer was shuffling his cars about as they do. All those super rich condition cold starts and short drives while failing to fully warm up the engine are what most likely killed the lambda sensor, the failure is actually an indirect consequence of the low recorded mileage not a reason to be disappointed with the lambda sensor's perceived short service life.

It’s also worth pointing out the Duratec Plus 4 runs an ancient technology narrow band lambda sensor that can only read, or is at least only accurate at stoichiometric ie 14.7:1 AFR. This in itself can mean big lean/rich swings in AFR and is not good for lambda sensor life, older narrow band lambda sensors are also fundamentally not as robust as more modern wide band lambda sensors like a Bosch LSU 4.2, or the even more robust and newer LSU 4.9 I run in conjunction with my ECU Masters EMU Black plug and play ECU.

As we can see there's a lot more to consider here before laying the blame at the door of supermarket fuel, which at the end of the day has to be very high quality or it would never reach the very strict British standards it must pass before being sold to the general public.

My final point would be you can actually clean poisoned lambda sensors and often with good results, if the OP had carefully cleaned his sensor and then taken his Morgan for a good old traditional ‘Italian Service’ (get the engine properly up to temp and drive it under load) then he probably could have saved himself the cost of a new sensor. The easiest way to clean the Lambda Sensor and catalytic converter that can also become poisoned for the same reasons, is by using a good quality catalytic converter and lambda cleaner fuel additive into the fuel tank, although removal and soaking the sensor in a suitable agent for a couple of hours tends to work best.

Newer lambda sensors tend to have a pre heater to warm them up quicker to help reduce emissions being too high from cold. If the heater fails then the ecu would probably pick it up as a fault. The Gems system on my Plus 8 did this and the OBD tester showed the fault correctly as a heater circuit failure. Luckily the Autel Maxiscan had the ability to do running checks and voltage readings from the sensors confirmed which of the two downstream sensors was faulty. Being downstream of the Cat meant the engine was unaffected as the upstream ones did that job. The downstream ones just checked the effectiveness of the cats themselves. The only problem was getting the old one out ! I jibbed out and got the garage to do it and also put a new sump gasket on at the same time. Easier than me crawling under the car.
I’ve still got a spare sensor so when I get round to sorting the trad parts I have I’ll sell them on.
I might check if the Maxiscan works on the Plus Four. It’s not upgradable for software any more so might not link. It has proved a good time, effort money saver over the years. My 1993 4/4 had a Ford 3 pin OBD system and I had a Draper reader for it. Never needed and sold years ago.