Power Steering Failure Polo 9N3 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 from making diagnoses that are based on guesswork and unnecessary part replacements.

The following issues are occurring in a 2007 Polo 9n with a 96 kW TDI engine:
I always had the climate control, radio, and lights turned 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 is still running. 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 I notice 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.
Part: 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

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

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, which would be difficult to find.

Please find the complete log file of 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 actually 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 the steering angle sensor are not covered, according to the manufacturer's statement .

What I've already checked: Battery ground cable (connection). Fuses (high-current fuses near the battery) (connection).
The battery voltage is 12.7V. When the alternator is charging, the voltage increases to 13.XV. 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.

look at this: https://community.dieselschrauber.org/en/viewtopic.php?t=20549

Keyword --> Undervoltage

Okay, thank you. I've removed the battery once, but I haven't found the power steering pump yet .
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 photo I forgot to include with the previous post...

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 in that corner down there.

Okay, I saw that you can access it by removing the wheel arch trim. I'll 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 is possible to remove the pump without removing the bumper, this requires disconnecting the lines to the steering rack (which can be quite messy), loosening the pump's bracket from the vehicle body, and carefully rotating the pump to disconnect the electrical connections.
In the meantime, disassembling the bumper is easier 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 the motor.

Okay, thanks, I'm going to remove the bumper. The annoying thing is that I still have a warranty from the VW 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 hooks, and as a result, they are hanging loosely above the battery... It's not great if everything is wobbling around while driving.
The threaded bushing on the lower battery holder, which holds the air filter box, is also broken.

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 is the red locking 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 the connectors clean and not green? Are the rubber seals in place and in good condition in the connector housings and cable glands? You can buy replacement connectors individually, but that won't help because the corresponding connector on the pump is also broken.
Cable ties still work, though. Regarding pumps, you can find new ones at horrendously high prices from , or refurbished units from maintenance companies (Google can help) at half the new price.

Yes, the contacts are clean 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, because 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 the online marketplace earlier, but I'm sticking with cable ties .

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 at the top of the battery; I cleaned it and measured 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.
The flickering of the headlights is still present.

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

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

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

Wurschdler wrote:

Earlier, I noticed that my steering wheel is not aligned properly, even though 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.
"Error in the braking/ESP control unit:"

The steering angle sensor located in the upper part of the steering column 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 a workshop visit due to the driver's airbag and the need to recalibrate the steering angle sensor. A prerequisite is that the axles are aligned.

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 allowed me to clearly hear the pump.

According to the VW 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 (TPL) from Volkswagen, some grounding points still need to be cleaned.
That's probably significantly more than I've cleaned so far.

If your Polo is exhibiting the following issues:

- Flickering of interior lights/radio lights/headlights when the brake pedal is pressed.
- Intermittent failure of the power steering system, followed by the steering wheel warning light illuminating (the error disappears after restarting the engine, or sometimes even without restarting 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 onboard 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, on the other hand, accuses me of deliberately causing the errors. Fortunately, he has a good foreman who is on my side and knows about Polo Pappenheimer....

I could have saved myself all that screwing around this weekend...
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 a mystery to me.
It can't be right, because the Polo has an additional rod in addition to the power steering, and that's 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:

Make sure to also check the ground cable from the battery to the frame and the motor.

"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. You'll need to replace the cable. 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, but the experiences gained could 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. It can't be true, because the Polo has an additional linkage in addition to the power steering, and that's what the TÜV requires... does anyone have an explanation?

Possible causes: Incorrect alignment, completely defective rubber bushings, or the steering wheel not properly installed.
The steering is only hydraulically assisted via a rotary valve control, and everything from the steering wheel to the wheels is directly connected.