Depollution System Faulty

[c4user4]

Dears,

 

In my Citroen C4, 1.4 petrol (hatchback 2004), just a few seconds after I start the car the message "depollution system faulty" appears on the screen and the engine management light stays on. For most part the car behaves normally, expect that now in low revs (for example behind a traffic light) it jitters and loses its power and some times even turns itself off.  But when driving in speeds higher than 40 kph it is just fine.

 

The probelm started two weeks ago. I had forgotten the car lights on which drained the battery. I called road assistance who jump-started the car by using a battery-boost. he told me to drive for 2 hours in gear two rev 4000 to charge the battery and I did.

 

Two days later the "depollution system faulty" problem appeared. Seems that these two are related.

 

Anyone can describe what is the problem with my car? Which part is faulty and how should I resolve it?

 

Thanks you very much

 

ps. my car screen looks like this: http://blogimg.goo.ne.jp/user_image/40/af/93d515c3f1f0f9b706e87257396fa429.jpg

 

 

[paul.h]

Welcome to the forum.

 

The only way to find out what is wrong is to use a code reader to read the fault code which will give a good indication of the fault. Any other way apart from an obvious bit not being connected or is damaged (look under the bonnet) is to replace lots of parts in the hope of finding the faulty one before too much money has been spent.

[c4user4]

Thanks Paul.
What is the cheapest code reader you would recommend for my engine? Citroen C4, 1.4 petrol (hatchback 2004)

[c4user4]

Code reader shows "Lambda Sensor" error. 

 

What does it mean? Can I clean this sensor? How can I access it?

[paul.h]

To check the lambda sensors you will need a code reader with live data. The sensor on the exhaust catalyst inlet (maybe listed something like lambda 1 or O2 bank 1) should be showing about 1.0 and switching continually up and down a bit if it is ok. The sensor after the catalyst (lambda 2 or 02 bank 2) should stay steady but if it switches similar to the inlet one it means the catalyst needs replacing.

 

The sensors can not be cleaned but check the wiring and connectors in case these are at fault and not the sensor. Of the 2 sensors, the inlet one could affect performance since it continually adjusts the fuelling but the outlet one just checks if the catalyst is working. So if you need to replace a sensor it is likely to be the inlet one - beware that cheap copy sensors may not work as well as dealer parts.

[c4user4]

So if you need to replace a sensor it is likely to be the inlet one - beware that cheap copy sensors may not work as well as dealer parts.

 

Thanks Paul,

 

So after some time, I decided to change the Lambda sensors. Could you please let me know which one is the inlet sensor? The one in the top or the one in the bottom? (see the diagram below)

 

 

Could you also guide me how to reach that sensor and take it out?

 

thanks

 

 

 

http://i68.tinypic.com/2vvwajn.png

Edited December 16, 2015 by c4user4

[paul.h]

The inlet sensor is part 1 in the diagram.

 

From the Haynes manual you can clearly see the sensor in the middle of the heat shield at the front of the engine on the top of the exhaust manifold as shown in your diagram. To remove it it says to disconnect its wiring connector and then unscrew the sensor and remove it and its seal which should be replaced. It says to apply a smear of high temperature grease to the sensor threads before fitting - this could be copper grease as used on brakes. The wire should be put back in any support clips so it does not touch the heat shield, etc.

 

If you still have the code reader I would check the fault code again, just in case it has changed and also look at the lambda sensor live data to confirm the fault - otherwise there is a risk you may be replacing the wrong part.

[Claire wants a new car]

This happens to me every winter. Unfortunately often occurs when driving on a motorway. Very scary. I've had it fixed at expense only for it to happen again. The last time it happened on the M4 in April with a car full of kids, it sorted itself out. A real big bear for this model.

[paul.h]

Welcome to the forum.

 

If your car is a diesel it could be the particulate filter (dpf) in the exhaust that is blocking up, if it has a dpf. However, it could also be many other causes. It would pay you to use a code reader to see what fault the car has registered, at around £10 to £40 these can be bought for a lot less than the cost of a diagnostic check at a garage eg https://www.gendan.co.uk/product_FXNT200.html