Approaching to cause of various warning lights (Citroen C4, ABA-B5NFU, ABS EPS depollution system faulty)

In the intense heat of every day, there are many troubles of the electrical system of the car.

I have heard from a citroen C4’s owner.

C4 has caused trouble, so please let consultation.

About three days ago, i heard a warning sound while driving, and for a moment, I got a Braking system and ABS/EPS error on the display.
After disappearing quickly, I was able to run normally, but I got a similar warning today.

When I connected the PC and saw the diagnosis, it came out in various ways, but there were a lot of errors such as fault of the speed information of the vehicle, abnormal speed information of the rear left and right was transmitted to ABS, etc.

I feel that the ABS speed sensor of the rear is suspicious when I receive it at face value, but what about it?

There is a video that examines the ABS sensor in the tester on youtube, and I wanted to try it, but I was afraid to dive and stopped it.

Other errors related to ECU supply overvoltage and headlights have appeared.

I thought that the dealer might be better because it seems to be a little confusing, but I would like to ask you if it is only so to see.

I'm sorry for the length.Best regards.

MY2009 ABA-B5NFU NFU AL4 Mileage 68,000km

In the past, various warning lights were displayed and the Citroen C4 was diagnosed because it could not be restarted by stalling the engine.

Citroen C4 Engine Malfunction (GH-B5RFJ)Citroen C4 engine malfunction was a surprising cause (GH-B5RFJ)

After that, I learned that citroen of this age, a bug inside the fuse box called Peugeot's demon gate, it was that a mysterious phenomenon occurs in various ways.

If you are travelling on this C4, you have your own PC-based diagnostic machine.Providing defect information enables a rough (remote) diagnosis prior to receipt.

In addition, since you are familiar with the structure of the car and the names of each part, you can share a lot of information in short sentences, and the time to approach the cause can be greatly reduced.

Now, because it is that various warning lights are turned on again this time, is the internal failure of the previous fuse box doubted?The fact that the warning display is running as usual even if it comes out is different from the past.

First of all, I will look at the fault log sent to you.

I asked them to record the current fault code, erase everything, and then check the fault code again and send it to me when the warning light appears.

citroen_C4_fault_record_20190801

The first thing we focused on here was the supply voltage supplied to the ECU.

17.0V and 18.0V, indicating unusual highs.The voltage that is usually adjusted during engine operation is around 14V.Even if there is a short circuit or disconnection in the suspected fuse box, it will not be a voltage greater than 14V.

One possible cause is an IC voltage regulator that can no longer be adjusted for voltage.The power element contained in the regulator often fails in the short circuit mode, but since it was the first pattern to return normally, i tried to replace the alternator with the IC voltage regulator after explaining to the customer.

I prepared it made by Valeo.It was made by Mitsubishi Electric that was originally attached.

At first glance, it is a position that seems to be easy to take out, but the wrench does not enter the bolt near Ekimani.

The combination which is not used frequently is twisted with acetylene, it bends into a crank shape, and a special wrench is made suddenly by welding the round bar.

In this way, the gap can be sewn and the bolt can be tightened by a narrow gap.

Unfortunately, it was not overvoltage at the time of check-in, and it was not possible to observe the defect.Because it was said that the warning was displayed several times a day to once every few days, I decided to ask the condition after delivery.