Sporadic power steering failure, Polo 9N3 BLT TDI

Hello everyone,

First of all, I'm new to this forum and a bit lost. I bought the Kaufmann diagnostic tool for self-help, and to prevent aimlessness and pointless part replacements by .

The following issues are occurring in a Volkswagen Polo 9n with a 96 kW TDI engine, manufactured in 2007:
I always had the climate control, radio, and lights on, due to the car's dark color.
(Which means a lot of work for the vehicle's electrical system.)

Last Friday, while driving in city traffic during extreme heat, the Polo stalled at a red light, and the steering wheel warning light came on. After restarting, everything seemed normal again. I didn't notice any loss of power steering because I was just approaching a red light.

As I'm driving on the highway, the power steering fails again.
This time, the light is on again and doesn't turn off. The engine continues to run normally. I haven't checked the radio or air conditioning. After a restart, everything is back to normal.

At night, I drive back home from my visit and discover that while the power steering is working, the headlights flash briefly every time I press the brake pedal.

Here are the errors I found today while reading the data:

Address 03: Brakes
Label file: RKS\6R0-907-37x-ESP.lbl
Part number SW: 6Q0 907 379 AS, Hardware number: 6Q0 907 379 AS.
Component: ESP 8.0 front H05 0003.
Revision: 00000000 Serial number: 00000000000000
Encoding: 0002491
Operating number: WSC 00788 785 00200
VCID: 8E1518009A4CC49

"One error found:"
00778 - Steering angle sensor (G85).
008 - implausible signal - sporadic.
Environmental conditions:
Error status: 00101000
Error priority: 2.
Error frequency: 2.
Lost Count: 216
Mileage: 74,852 km
Time: 0.


Address 09: Body Control Module - Label file: RKS\6Qx-937-049-C.lbl
Part number: 6Q1 937 049 F.
Component: 0009 BN-SG. 2S36
Encoding: 09390
Operating number: WSC 00788.
VCID: 3E7508C03A6C949

Sure, here is the translation of the text from German to English:

"2 errors found:"
01598 - Voltage of traction battery.
27-10 - implausible signal - sporadic.
01598 - Voltage of traction battery.
07-10 - Signal too weak - Intermittent.

Address 44: Steering assist
Label file: RKS\6Q0-423-156.lbl
Part number: 6Q0 423 156 AB
Component: Steering assist TRW V270.
Encoding: 10120
Operating number: WSC 00788.
VCID: 6FEBE5842D862D1

"One error found:"
00566 - Steering assist system operation.
27-10 - implausible signal - sporadic.

Occasionally, I get a little worried because there might be a ground fault somewhere in the car that is difficult to locate.

Please find the complete log file for the vehicle attached.
Has anyone else experienced a similar problem?
I would also be interested in hearing opinions about the BLT Polo TDI.
The car is already giving me some trouble, and I'm used to better quality from my 5 Series wagon.

Edit: I've only had the car since January, and it's still under warranty, but things like steering angle sensors are not covered by that warranty, according to .

What I've already checked: Battery ground cable (connection). Fuses (high-current fuses near the battery) and their connections.
The battery voltage is at 12.7V. When the alternator is charging, the voltage rises to 13.X V. With all consumers turned on, I let my girlfriend drive while the engine was running and checked the voltage for any drop. There was only a brief fluctuation on the multimeter, nothing more.

[Translating...]

sieh mal hier: https://community.dieselschrauber.org/en/viewtopic.php?t=20549

Stichwort --> Unterspannung

Okay, thank you. I've removed the battery once, but so far I haven't found the power steering pump .
Is that still attached to the metal bracket from which the green screw cap for the servo oil protrudes?

"If so, the bumper needs to be removed, and I approached it from the wrong side... See the photo."

Here's the forgotten photo for the post above...

Wurschdler wrote:

Is it still stuck under the metal bracket from which the green screw cap for the servo oil protrudes?

Yes, it's wedged down there in the corner.

Okay, I see that you can access it by removing the wheel arch liner. I'll take a look and see if I can find that blue connector.

Since the electrical connections (3 plugs) on the pump unit are located at the front, you can only access them by removing the inner wheel arch lining. To properly inspect the electrical connections, the bumper must be removed. While it's possible to remove the pump without disassembling the bumper, this requires disconnecting the lines leading to the steering rack (which will result in a significant mess), loosening the pump bracket from the vehicle body, and carefully rotating the pump to disconnect the electrical connections.In the meantime, it's easier to remove the bumper if you only want to check the connectors for corrosion.

Make sure to also check the grounding cable from the battery to the chassis and motor.

Okay, thanks, I'm going to remove the bumper now. The annoying thing is that I still have a warranty from the Volkswagen dealership on the car, so hopefully nothing breaks while I'm working on it.

Yesterday, while reinstalling the battery, I also noticed that the plastic parts that hold the fuses in place on the battery are all broken at the snap-fit points. This means they're hanging loosely above the battery... It's not ideal if everything is wobbling around during driving.
The threaded bushing on the lower battery holder, which secures the air filter box, has also broken off.

The following errors were found:

- The double mass damper, which is attached to the body near the pump, was corroded. The corrosion was removed using abrasive cloth.
- The middle connector on the power steering pump (the larger one) can be plugged in, but it doesn't click into place! Upon closer inspection, I noticed that the locking tab on the power steering pump is broken, as well as the red retaining clip on the connector. Therefore, the connector is not properly secured.

The question is now whether I can get the plastic part on the pump and the connector separately, or whether I need a new pump and connector anyway... I have also thought about a solution using cable ties....

See also the photos.

Are the contacts on the pump and connectors verschandeln and not green? Are the rubber seals present and in good condition in the connector housings and cable glands? You can buy replacement connectors individually, but it won't help because the corresponding part on the pump is also broken off.
Cable ties still work for this purpose as well. Regarding pumps, you can find new ones at exorbitant prices from , or refurbished units from maintenance companies (a Google search will help) at half the price of a new one.

Yes, the contacts are verschandeln and in good condition, as are the seals.

The cable tie solution has now been implemented, and the bumper is reattached (quite a job to do alone ). It's annoying that the connector no longer clicks into place; it definitely must have been like that already, considering how carefully I pulled the connector out... (Providing proof will certainly be difficult).

I checked out some pumps on eBay earlier, but I'm sticking with the cable tie .

I measured the continuity of the ground cable at the bottom and cleaned it to remove any corrosion. I did the same for the ground cable connected to the battery at the top, cleaning it and checking its continuity. There was a lot of dirt there as well.

Earlier, I noticed that my steering wheel is misaligned even when the wheels are straight. It's probably the steering angle sensor then.
The flickering of the headlights is still present.

Can you install a steering angle sensor yourself?
Is there a standard steering rack available for the Polo without power steering?

Then I would throw out all that electronic junk! It also saves weight...

By the way, a big thank you to you, Red, and to everyone else as well .

Wurschdler wrote:

Earlier, I noticed that my steering wheel is not aligned properly even when the wheels are straight. !:

How does it work? Steering angle sensor: located on the steering gear.
Steering angle sensor: located in the steering column switch.
The error message in the braking/ESP control unit indicates:

The steering angle sensor located in the upper part of the multi-function stalk is reporting an angle that does not correspond to the wheel speeds.
Centering the steering wheel (aligning the wheels to a straight position) requires professional service due to the driver's airbag and the need to recalibrate the steering angle sensor. It is essential that the axles are aligned correctly beforehand.

You can also listen to the power steering pump on its own, without the annoying engine noise. To do this, I stalled the engine while driving slowly (perhaps 20-40 km/h) in 5th gear. This made the sound of the pump very noticeable.

According to the Volkswagen dealer, the error has been found.

The main cable that runs from the battery to the chassis is likely defective or undersized.
According to the technical problem solution document from Volkswagen, some grounding points still need to be cleaned.
That's probably significantly more than I've already cleaned.

If your Polo is exhibiting the following issues:

- Flickering of the interior lights, radio illumination, or headlights when the brake pedal is pressed.
- Intermittent failure of the power steering system, followed by the illumination of the steering wheel warning light (the error disappears after restarting the engine, or sometimes even without a restart after a short time).
- The radio just turns off.
- The engine simply shuts off and all electrical components fail (due to a collapse of the on-board voltage).

Then it has something to do with the grounding points and the main ground cable of the car!

I will ask for the after the TPL number.

The boss, by the way, accuses me of deliberately causing the errors. Fortunately, he has a good foreman who is on my side and knows about Polo Pappenheimer...

Die ganze Schraubaktion am Wochenende hätte ich mir dann sparen können ....
Well, at least I was able to secure the connector for the servo pump... Otherwise, it would have come loose eventually...

However, the angle of the steering wheel when the wheels are straight is puzzling to me.
It's not possible; the Polo has an additional rod in addition to the power steering system, which is what the TÜV (German technical inspection authority) requires... Does anyone have an explanation for this?

I will report on the success or failure!

Best regards,

RedR32 wrote:

Unbedingt auch das Massekabel von der Batterie zum Aufbau und Motor prüfen.

"It's probably corroded and should have been noticed by you. If the copper wires are corroded, simply cleaning the connection points won't be enough; new cables are needed. The wiring is relatively easy to replace, and it doesn't cost a fortune."
Since you inquired about the , you might get it for free.

Quote:

I could have saved myself all that screwing around on the weekend

.

I wouldn't say that; the experiences gained can be useful.
I've seen pumps that were flooded before.

Quote:

The angle of the steering wheel when the wheels are straight is something I find puzzling. Kann ja gar nicht sein den der Polo hat doch ein Gestänge zusätzlich zur Servo, den das schreibt der Tüv doch vor.... weiß da jemand eine Erklärung ?

Possible causes: Incorrect alignment, completely defective rubber bushings, or the steering wheel not properly installed.
The steering is only power-assisted by a rotary valve control; everything from the steering wheel to the wheels is directly connected and transmits force mechanically.