ESP Log: Speed Drops in Main Line

Hello,

In the ESP log of the Polo, the value from the front left wheel speed sensor (VL) intermittently jumps to exactly 16.5 km/h.
In the instrument cluster (KI), absolutely nothing is displayed – neither warning messages nor active indicator lights.

I will still take a look at the wheel sensor installation and the ESP error memory, and I will provide an update afterwards.

Does anyone recognize these symptoms, or can anyone suggest where I might be able to find information about them?

Update:

1. The ESP-FS is, of course, empty. When the sensor cable is disconnected for testing, an error message is immediately generated.

2. The wheel sensors seem to be intelligently designed, both in terms of their construction (and because no through resistance could be measured - I had both rear wheel sensors removed for comparison), as described, for example, in http://www.kfztech.de/kfztechnik/elo/sensoren/drehzahlsensor.htm.

For additional functional testing, I also logged data from both VA sensors while manually overdriving them. For each sensor, not only the speed signal is available, but also three additional values in the µsec range. I have added both logs to the original post as the second sheet in the download.

Nevertheless, I still have no idea how to interpret the individual 16.5 km/h values that are scattered throughout the driving log, and how to attribute them specifically to the VL sensor .

The ABS control unit occasionally displays a vehicle speed value that VCDS reads as 16.5 km/h.
interpreted. Meaning... perhaps actually 16.5 km/h.
Perhaps it's the status of all four sensors, or something completely different.
Perhaps it's just a software bug in the ABS software. Until that's fixed...
If it continues to be a problem (and it clearly isn't), the manufacturer will...
avoid the costs of re-certifying the software, and VW can save itself...
Replacement of all control units, provided they were not officially accessed via the diagnostic tool.
Updates are allowed (or at least used to be the case with ABS and airbags; it's unclear whether...).
Whether that is still current, I cannot say.

The incorrect values are not always 16.5 km/h, but also include 14.4, 26.3, and 26.4 (in a different log).
In addition, the HL sensor (which is much less common) may display a false value of 0.

A comparative log from our Rapid, recorded over approximately 15 minutes using the same wheel sensors (but a different ESP system), shows only single instances of incorrect readings from the VR (virtual reality) and HR (heart rate) sensors.
For comparison: While running for 15 minutes, the Polo generates approximately 15 incorrect readings on .

Attached are the overall images of both logs. I don't think the Excel files are very informative.
Every downward spike indicates a faulty sensor reading.

Edit:
".gif" image uploads are no longer working???
I'm only seeing black areas, but the approximate sizes of the images seem to be correct.

Hi Ulf,

Uploading .gif files should be working again now, thank you for the notification! Unfortunately, I have no idea about the 16.5 km/h issue.

Best regards, Rainer.

GIF upload test.

ulf wrote:

The incorrect values are not always 16.5 km/h, but (in another log) also 14.4; 26.3 and 26.4. In addition, the HL sensor (which is much less common) may display a false value of 0. A comparison log from our Rapid system, running for approximately 15 minutes with the same wheel sensors (but a different ESP system), shows only single instances of incorrect readings from the VR (virtual reality) and HR (head-mounted reality) sensors. For comparison: While running for 15 minutes in Polo, there are approximately 15 incorrect values on

.
Status values won't be used in that case.
Is the Rapid ESP a more recent development? Has the software been revised?
On the other hand... what is the transfer rate? 2 to 6 Hz?
Das wären dann eine Fehlmessung auf 120 .. 360 Messungen. Error rate below 1%.
The software should be able to handle this without generating any alarms or errors.
Even if it's difficult - try to ignore it .

Wiesel wrote:

Is the Rapid ESP of a more recent development date? Has the software been revised?

Where can you see that?
The Rapid is a 2015 model (manufactured around January 2015), and the Polo is a 2014 model (manufactured in the summer of 2013).

Quote:

On the other hand... what is the transmission rate? 2...6 Hz?

Polo: approximately 3.8 Hz, Rapid: approximately 3.4 Hz.

Quote:

Even if it's difficult - try to ignore it

. It's hard... *grumble*.
But thank you for your assessment .