power lag issues

2006 Citroen C3 1.4 HDi (pretty certain it's the 8V)

We have had ongoing power lag issues with the vehicle for a long time. I sent the vehicle for a full diagnostics which yielded no fault codes. My private mechanic, the citroen workshop manager and my turbo mechanic have all test driven the car and confirm that there is a acceleration lag problem. The turbo has been tested and is fully functional. The CAT has been removed.

I eventually (this morning) discovered this article https://www.wheelsjoint.com/citroen-c3- ... diagnosis/ which lists several symptoms of a faulty O2 sensor. My vehicle shows the following symptoms out of that list:- slow acceleration, loss of power, engine hesitation, jerking when accelerating, high fuel consumption, foul odor. So I am heavily leaning towards the likelihood that the vehicle has a bad O2 sensor.

I attempted to search the forum (unsuccessfully) to source the following information:-
1) Where to locate the O2 sensor?
2) How to test with a multi-meter?

Assistance and comments are welcome.

Apologies, I'd also like to know the part number for this specific vehicle so that I can order the correct thing.

Hi

You say your car is a diesel

The O2 sensors are only found on the petrol engines.

You need to look at the diesel faults for diesel engines.

Firstly be very sure which engine you have, rather then guess. You can attach an image of your engine to the forum, (not someone else's engine) to help with identification.

Then give a description of the fault you have, when it happens and if you can force it to happen by doing anything in particular while driving.

Thanks for your reply. Yes, I discovered that my diesel only has an airflow sensor.

I can't recall if I mentioned it in my original post but there are no fault codes after completing the diagnostics, which was undertaken by an approved Citroen dealership in my region. That same workshop manager took the car for a drive and confirmed that there is definitely a problem even though they did not receive any diagnostic faults. (It seems that nobody wants to attempt repairs unless the computer tells them to).

The closest, therefore, that I have found that matches the symptoms that the vehicle has, points to the O2 sensor. Power lag, hesitation on acceleration, loss of fuel economy etc.

I think I may have mentioned that neither my private mechanic, the dealership nor the turbo specialist are able to pinpoint the precise the fault. So I am forced to experiment. Can the airflow sensor have the same symptoms (on my diesel) as an O2 sensor would have?

DevineSA wrote: ↑Thu Mar 02, 2023 8:28 am Thanks for your reply. Yes, I discovered that my diesel only has an airflow sensor.

Can the airflow sensor have the same symptoms (on my diesel) as an O2 sensor would have?

Please don't mention the O2 sensors as they are for the petrol engines. You need to focus only on the diesel faults and how they affect the engine.

Mixing the petrol engine parts with the diesel engine parts will get you, exactly, nowhere.


A faulty MAF can give a low power and is often accompanied with a P fault code for it.

The quickest way to test the MAF on the diesels is to just disconnect it.

This will log a fault, but it also forces the car to use the default data from the missing MAF and the car runs very well with it disconnected (electrically) - don't actually remove it from the car.


If the car starts to work properly with the MAF disconnected (unplugged) you can be sure the fault is the MAF and just cleaning it can be a good first step, other than that, change the MAF or leave it disconnected.

If you attach a picture you take of the engine it can help identify which one you have.

Yes, apologies again, I realise that I only have a MAF in my engine.

Is it possible for faulty fuel injectors to cause the same symptoms? (Hesitant pull-off, unnecessary stalling, poor power in low revs in all gears, terrible fuel economy, slow acceleration, jerking when accelerating. foul odor)

C3driver52 wrote: ↑Thu Mar 02, 2023 2:48 pm

DevineSA wrote: ↑Thu Mar 02, 2023 8:28 am Thanks for your reply. Yes, I discovered that my diesel only has an airflow sensor.

Can the airflow sensor have the same symptoms (on my diesel) as an O2 sensor would have?

This will log a fault, but it also forces the car to use the default data from the missing MAF and the car runs very well with it disconnected (electrically) - don't actually remove it from the car.


If the car starts to work properly with the MAF disconnected (unplugged) you can be sure the fault is the MAF and just cleaning it can be a good first step, other than that, change the MAF or leave it disconnected.

The turbo specialist disconnected the MAF and I drove around for the day like that. The car did eventually pop up with a "anti-pollution" fault BUT the performance was unchanged. It still had the same symptoms. So I reconnected the MAF at the end of the day.

The vehicle is currently at a different mechanic who wants to start by replacing all the injectors at £500 each. Is it possible that injectors could be giving all these same symptoms?

You don't test injectors by changing them, considering their cost.

Do testing before changing parts, it can work out cheaper in the end.

Test injectors with a leak-off test first. This can pinpoint a single or multiple faulty injector to change if they shows up.

Reading the codes and live data for fuel etc can also help identify problems with fuel.

Any update with the photo of your actual engine fitted?

Just pop the bonnet and snap a photo