Failed MOT on emissions

Hi all, my 2002 Jimny has failed the MOT on very high emissions at idle. I have noticed it idling at high revs at start up the last while and after failing, I checked the lamda sensors and noticed the one after the catalytic converter was completely rotted and broken away. I can't find anywhere that stocks the exact model, and in fact, I can't find the model number either. Can anyone point me in the right direction please and will this sort the emissions problem? TIA

They don't last forever and manufacturers suggest 60 to 90K miles, but external factors can also kill them. I would feel confident that it will fix your problem so long as the exhaust mount and CAT are in good order. Its the correct starting point anyway, fix the problems you can see before you look further. If you intend to keep the car don't skimp on this part, Denso or branded will work for another 20 years, cheap as chips sensors may / may not work long, but I appreciate you can only go as far as spare cash allows.
Unfortunately I can't help with the part number, but someone will be along to help with this I am sure.
 

Just had a quick Google
Check out GENUINE SUZUKI 02 LAMBDA SENSOR 18213-56KB0-000 on eBay!
Sensor


They claim to a Suzuki agent and ask for you registration as a check the part will fit. Ask them, if they say yes you can purchase, or use the part number in the photo to find alternatives. Good luck.

The lamda sensor AFTER the catalytic will not cause high emissions - it's function is to monitor the converter efficiency, to diagnose the cause of the failure you need to look at the emissions numbers - what specifically did it fail on CO or NO?

As Fordem says, sensor 2 just checks catalyst efficiency.

An exhaust leak post catalyst will cause high lambda readings

Sensor #1 (the manifold) is a common failure on a Jimny, they go out of spec. and the ecu runs upto maximum fuel trim in closed loop, so then the open loop map is shifted and the fuel consumption nosedives across the board.

High CO is over fuelling from a duff sensor #1, high HC is a missfire which may be an over-lean or over-rich mixture due to a duff sensor #1 or an ignition problem.


If you want to throw money at it, change sensor #1, the generic ones work fine, I bought the cheap one that comes without a plug, and I had to cut my lead and crimp it to the new one.

I think it is 4 wire, I can't remember.

Thanks guys, great help, appreciated. It failed for CO at low idle (1.19 vol%) and high idle lamda was out too (1.05, range is 0.97-1.03). Its revving very high at idle so this suggests the o2 sensor at manifold then?

The high lambda will be an exhaust leak after the catalyst.
If it was a leak before the catalyst the CO would be down as the extra oxygen would convert it to CO2 inside the catalyst.

The high idle is a concern, could be an air leak at the manifold- is the pipe from manifold to vacuum tank intact, and no leaks at the vacuum solenoids, you can try just capping the fitting at the manifold, obviously the vacuum hubs wont work with the pipe disconnected.

The High CO is overfuelling, very likely the manifold sensor.



You need to sort the post-cat sensor too, as an obviously defective sensor is an MOT fail (major), whether or not the emissions are correct.

Leak at the manifold is a strong possibility. I had an engine put in after the last one blew the head gasket. Since then it has been running very high revs at idle, over 1000rpm, goes to 2,000rpm at start up but drops to just above 1,000 after about 15 seconds. This points to leak at manifold yes?

Not necessarily.

Normally you only deal with one problem at a time.

I thought the problem was the emissions had drifted high and nothing had been touched, which is likely the manifold sensor. High lambda and an obviously broken/missing post cat sensor just needs leaks fixing and a new sensor, so a pair of sensors and an exhaust repair would sort it.

Now you are saying it is a replacement engine that has never been right since fitting......


High idle is probably extra air getting into the engine that the idle speed system can't reduce.
It could be an air leak at the inlet manifold flange, a leak in the vacuum hub system or a pipe broken/leaking/fitted incorrectly. It could be the charcoal filter purge valve leaking or a pipe off the purge system. It could be the pipe to the valve I forget the name of that goes into the tappet cover. It could be a leak at the brake servo, or in the pipe from manifold to servo.

If someone else fitted the engine you need to check every pipe for

a) being there
b) being in good condition/not leaking
c) connecting to the right place at both ends.

It could also be the throttle cable is too tight, someone has messed with the adjustment of the throttle butterfly, the pedal sensor is out of adjustment and it thinks the pedal is pressed rather than released so it doesn't go into idle control etc.


Has it ever MOT'd with this engine and the high idle?

If it has, sort the sensors & exhaust and get the MOT.

Then fix the idle problem.

I checked all the hoses and everything seems fine, no leaks. But I did find a leak in the fuel injection hose. I've ordered a replacement. Would this be a possible cause of high idling and emissions?

Not unless the leak is bad enough to significantly alter the fuel pressure, a weep won't matter.


High idle speed is caused by extra air getting in, by accident or design. This is because there is a leak for air to bypass the throttle butterfly and idle control valve, or the ecu is setting the idle speed too high, because it thinks the engine is cold (faulty temperature sensor??) or it thinks the air-con is on, or there is a large electrical load (I think there is some sort of load sensing to bump up the idle speed, I'm not 100% though)

High CO is too much fuel. It could be the faulty manifold oxygen sensor, which is the most common reason on a jimny, or it could be excessive fuel pressure, wrong injectors (from a bigger engine), or again the ecu thinking the engine is cold and basically running on choke. There is also another option- leaking exhaust manifold.

High HC is unburnt fuel, due to a missfire- could be caused by over lean or over rich, or ignition fault. (you haven't got this)

High lambda is too much oxygen in the exhaust , 99% it is due to an exhaust leak, I said post-cat because you said the oxygen sensor was broken and there was corrosion.

However, it could be a leak in the exhaust manifold before the first oxygen sensor.

This makes the sensor read lean, so the ecu increases the fuel, increasing the CO, but the lambda will still be too high as well!



What this boils down to is that there is a lot that can go wrong, and blindly chucking money at it changing stuff can be a waste of money.

However, the reason I said change the manifold oxygen sensor is because

1) They are cheap (generic ones that work anyway )- cheaper than paying for a code read, nevermind a session at a garage
2) Dead easy to change
3) Commonly fail.


If it isn't the manifold oxygen sensor, and you have eliminated all possible inlet and exhaust leaks, then you have to start reading and interpreting live data, to find out what is going on.

Lambda sensor is ordered and on the way. In the meantime I checked for leaks and removed the throttle body to clean the IAC. Everything looked clean and could not find leaks. Is the noise in the attached video normal?
youtube.com/shorts/WWSVr05AKZY?feature=share