Help Needed With An Engine Fault Code

[vikvallabh82]

Hi all. For the second time in one week I have had a Fault code 'P0420 - Catalyst System Efficiency below Threshold' come up whilst driving. the conditions are as follows:

Going at approximately 70mph on a motorway

Always happens when I'm past half way on the petrol gauge (not sure if it makes a difference but thought I'd put that in)

At first I thought it was a bad batch of fuel, so i boycotted the petrol station and used others. i got the error last Thursday had it cleared and gave her a full tank of Shell regular with some Redex Petrol system cleaner (thinking it might be coked up sensors of injector. And lo and behold it happened again today!

My friendly local independent garage ran an emissions test to see if the cat was on its way out, and it sailed through. everything was within limits.

Does anybody have any ideas as to the culprit or want to recommend the next steps for me to diagnose, I'm at a loss.

Vik

[leepulsar]

Hi all. For the second time in one week I have had a Fault code 'P0420 - Catalyst System Efficiency below Threshold' come up whilst driving. the conditions are as follows:

Going at approximately 70mph on a motorway

Always happens when I'm past half way on the petrol gauge (not sure if it makes a difference but thought I'd put that in)

At first I thought it was a bad batch of fuel, so i boycotted the petrol station and used others. i got the error last Thursday had it cleared and gave her a full tank of Shell regular with some Redex Petrol system cleaner (thinking it might be coked up sensors of injector. And lo and behold it happened again today!

My friendly local independent garage ran an emissions test to see if the cat was on its way out, and it sailed through. everything was within limits.

Does anybody have any ideas as to the culprit or want to recommend the next steps for me to diagnose, I'm at a loss.

Vik

ur cat has gone out of spec done loads

[MR LBe]

Hi all. For the second time in one week I have had a Fault code 'P0420 - Catalyst System Efficiency below Threshold' come up whilst driving. the conditions are as follows:

Going at approximately 70mph on a motorway

Always happens when I'm past half way on the petrol gauge (not sure if it makes a difference but thought I'd put that in)

At first I thought it was a bad batch of fuel, so i boycotted the petrol station and used others. i got the error last Thursday had it cleared and gave her a full tank of Shell regular with some Redex Petrol system cleaner (thinking it might be coked up sensors of injector. And lo and behold it happened again today!

My friendly local independent garage ran an emissions test to see if the cat was on its way out, and it sailed through. everything was within limits.

Does anybody have any ideas as to the culprit or want to recommend the next steps for me to diagnose, I'm at a loss.

Vik

ur cat has gone out of spec done loads

im getting the same code, what do you mean by cat has gone out of spec pal??

thanks

[mr-p]

it means that the ecu is detecting that the cat is not removing enough harmful gas's out of the exhaust gas. try taking out the lambda sensor after the cat and give it a clean, put it back in, disconnect the Battery and reconnect then go for drive and see if the light comes back on. sometimes the lambda gets coked up and cant get a proper reading

[vikvallabh82]

I will try the Lambda sensor clean... but if the cat had gone would it still be able to pass an MOT level emissions test?? The co level was 2, the allowable limit is 200, surely thats a sign that its working?

Vik

[mr-p]

nope it wouldn't pass an mot if the emissions were too high its a straight fail it could also be the temp coolant sensor giving an incorrect signal

[vikvallabh82]

which one is easier to take out the lamda sensor after the cat or the coolant temp sensor (the anser will obviously decide which one i get done first)

[Haze]

changing the temp sensor itself is easy except that you will have to drain the cooling system, just did it on my carina and its a messy job. Also the drained coolant is considered hazardous material and must be disposed properly at a recyling centre, Not down a drain because it's toxic in fairly small doses.

Cleaning the lambda sensor is worth doing anyway and is probably less hassle but dont shear the bolts when you're taking it off.

Can anyone tell me how to get the fault code on my leanburn 4AFE? ive read bits about crossing terminals in the diagnostic port and counting the blinks on the engine light,but if anyone has specific details or links to them (instructions, fault codes etc.)it would really help.

[Phil01]

bridge out T1-E1 and count the blinks with ignition on by the orange engine warning light/

Off the top of my head I think the code for the O2 sensor on lean burn 1600 4AF-E ( Manual trans Carina) not auto, was 21

[vikvallabh82]

Anyone got a guides or pictures to locating and removing the lambda sensor?

Same question for the Coolant temp sensor?

[Phil01]

o2 sensor is bolted into the exhaust downpipe and has wires coming out of it, you can not miss it.

It will not be a coolant temp sensor, even if it was, cleaning would not do anything as it is a sealed capsule.

[vikvallabh82]

cheers Phil, now to borrow a trolley jack and get it done

[Phil01]

being honest mate, removing o2 sensor will not do much either.

If it was me I would clean it by driving at a highish speed with a high engine rpm and a very light throttle opening, what you want to do is burn off the contaminates with a weak mixture by using the above drive cycle, NO wide throttle openings in a low gear

[vikvallabh82]

wide throttle openeings?? you mean without flooring it?

[vikvallabh82]

Ok... not sure anyone is still watching this thread or cares, I fixed the problem by cleaning my lambda sensor using Cataclean.

[mr-p]

[vikvallabh82]

Hang on a sec Mr P = its back the dreaded CEL.... I will try another bottle of Cataclean and see where i get to. I'm pretty certain its the sensor now. I have also just filled up with Tesco momentum Ron 99, to see if that helps.

[mr-p]

hopefully could be a few things. the eml went off because you disconnected the Battery so it may be the sensor but may not as the ecu has just picked up a fault again its not necessarily the sensor but got to start some where. really you want to use a diagnostics scanner that runs live data so you can see what there doing along with all the other sensors

[vikvallabh82]

Mr-P thats the thing.... I did NOT disconnect the Battery and the eml went off. I am going to get another two bottles of cataclean and try that again. If it works then I know if it is a gremlin in the "combustion path" as I call it.

[mr-p]

ahhh then that narrows it down a bit

[vikvallabh82]

Ok..... so two more bottles of Cataclean, and it didnt work :( I'm gonna have to spend some money and send it to a garage! boo :(

[mr-p]

really needs a diagnostic scanner plugging in

[saghersalim]

Hi Vikvallabh82,

Did you manage to sort out your car with Engine management issue (Cat problem etc)? I'm having exactly the same problem as yourself. Any help would be much appreciated.

Thanks