EML coming up when driving over 50MPH

Hello guys my citroen c3 1.2 pure tech having a little issue now. I recently had the cam belt replaced and full service has been done as well (had catalytic converter replaced 40k miles ago ). From the next day the engine management light started popping up every time I’m driving over 50mph. I did a scan and got below fault codes. My regular mechanic assuming it needs topping up fuel cleaner (redex or some other brand) to clear any clogging. The car drives absolutely fine. My question is do I need to worry about the alternator or O2 sensor ? Does anyone had encountered this issue if yes how did you sorted it?

Thank you very much

Hi

Delete all the codes that will go.

Take the car for a run over 50MPH and get the MIL to come on again

Then re-read the codes and if you can use google lens on the screen or just type them out for easier reading, quoting and copy and pasting etc.


You really need fresh codes because you probably have a load of historical ones in there too.

Thanks Arfur.

Yes deleted the codes already. This morning the mechanic added the redex, checked the alternator, battery and co2. And he road tested it. And I just drove 21 miles on motorway. The EML didn’t come. If it does I’ll probably delete it again.

*the mechanic didn’t charge me anything. He also asked me to come by after few days of driving for a further check.

C3puretech wrote: ↑Wed Aug 03, 2022 2:16 pm had catalytic converter replaced 40k miles ago

What happened to the old catalytic converter? Seems suspicious that you now have a P0420 fault.
Is your engine consuming oil? Poor fuel consumption?
Or is that an old code left over from the last time?

Sorry for the late reply.

OEM coverter changed 40000 miles ago (car is on 102k).

Yes the engine burns a lot of oils. I have to top up a litre every 10 days or so.

Never deleted any codes repeatedly.

Engine oil doesn’t mix with coolant or there’s any leak underneath. Went to 2 garages with experienced mechanics didn’t get any satisfied answer about this burning of oil.

Already added fuel Cleanser to clear the converter clogging but nothing the EML light came back the same evening. My mechanic advised a carbon cleaning if that doesn’t work then probably a new converter with o2 seniors.

Getting really really frustrated with this car now to be honest….

I'm sorry but I don't have any good news for you.

With the oil consumption that high it would damage a catalytic converter very quickly. The old one should not have been replaced with the oil consumption that high. To replace it again without fixing the burning oil issue is a waste of money (and a catalytic converter). A catalytic converter can stand a small amount of burning oil but after that it becomes irreversibly damaged.

My guess would be damaged liners and/or piston rings. They would need to be replaced.
"Carbon cleaning'' is only successful on direct injection engines. It's not applicable in your case.

Modern engines run VERY lean and VERY hot! It's imperative that a good synthetic oil be used from new. And that the oil be changed regularly!

The original converter was cracked at 62000 miles!
It’s replaced by a Citroen specialist..only because it’s a fair deal and it’s done on the same day.

Yes I’m aware of the piston rings but my mechanic checked the engine inside on last service 14000 miles ago and didn’t notice anything fishy and commented as Citroen are known for burning oils on their engines.

And surprisingly the mpg is absolutely brilliant. Car pulls fine. I drive 125 miles everyday.

I’ll add another wynn cleaner today and drive 150 ,miles and Going back to the local mechanic tomorrow. Let’s see what happens….

C3puretech wrote: ↑Wed Aug 10, 2022 12:45 am Yes the engine burns a lot of oils. I have to top up a litre every 10 days or so.

C3puretech wrote: ↑Wed Aug 10, 2022 10:06 am I drive 125 miles everyday.

This a quote is from a Citroen handbook:
MAXIMUM PERMISSIBLE oil consumption for a RUN-IN engine:
- 0.5 litres per 600 miles (1,000 km) for a PETROL engine.

Looks like your oil consumption might only be just on the edge of "think about investigating".

I noticed that ALL those fault codes are "temporary". Have you checked the "live data" on each of them to see when the fault(s) occurred? Did they all occur at the same time?
A temporary P0420 code is a bit strange!? It seems a bit weird that it comes and goes if the converter is damaged. Typically it's damaged or it's not damaged.
You could try and capture the downstream O2 sensor output when the car is driving.
You may be right and it could be the O2 sensor...but it's still weird.
My guess is the EML is coming on because of the P0420 error and not the alternator error.