Error 65535: External Pressure & Emergency Mode

Hi everyone,

My Passat also has a slight power issue, and it occasionally switches into limp mode.

"While logging data, I noticed the following: When the engine speed exceeds 3000 RPM, the boost pressure drops suddenly to approximately 690 mbar (from around 1130 mbar previously), and I receive the error code 65535, indicating a defective engine control unit. Subsequently, during the next acceleration, I get the error code 0575, which indicates a regulated intake manifold pressure issue, leading to the control unit being locked."

The outside pressure remains at this value as long as the error persists, which can only be cleared when the engine is "cold" (below 60°).

MKB: AHU
LLM and N75 sensors replaced - Hoses checked/replaced, air filter inspected/replaced.
"The turbocharger is easily accessible; the EGR valve is also easily accessible, the catalytic converter is clear, and the turbocharger spins freely."

Best regards,
Jones.

Hi,
I'm familiar with that error (unfortunately).
The cause is the height sensor in the engine control unit. Unfortunately, the only solution is to replace it.
Engine control unit

Best regards, Rudi.

Quote:

Error 65535, engine control unit (ECU) defective.

Yep, that's unfortunately correct. The pressure sensor is located in the control unit, and it's probably easier to get a working control unit from a junkyard than to find the sensor itself.

Best regards, Rainer.

I would like the old control unit for testing purposes if you are getting a new one (K-line protocol to the microcontroller), so please don't just throw it away!

Thank you for the quick (though not very pleasant) responses.
I will contact him shortly to find out when he is available.

Dj Ninja wrote:

..so, please don't throw it against the wall!

"No way - I won't do that, even though I might be tempted - maybe it still needs to be kept around as a source of spare parts."

lg jones

Thank you for the quick (although not very pleasant) responses.
I'm going to contact my right away to see when he's available...

Original spare part ?

Which car are we talking about? The prices range from around 800 to 1400 EUR.

Best regards,
Rudi

My is a friend of mine who has his own workshop, so let's see what he might have available.

It's a Passat wagon.

Jones1978 wrote:

When the engine exceeds 3000 RPM, the outside pressure suddenly drops to approximately 690 mbar (previously around 1130), and I receive the error code 65535, indicating a defective engine control unit.

Rudi wrote:

I am familiar with that error (unfortunately). The cause is the altitude sensor in the engine control unit. Unfortunately, the only solution is a new engine control unit

.
Hi Rudi,

That's a rather peculiar error pattern if it were only due to the altitude sensor.
"1130 mb is far too much external pressure, because the usual maximum (extreme high pressure at sea level) is probably around 1050 mbar, in my opinion."

690 mbar already corresponds to considerable altitudes (approximately 2500 - 3000 meters).

How can the altitude controller "sense" that the 3000 rpm threshold has been exceeded, and then switch from "stupidity" level 1 to "stupidity" level 2 ?

It's a Passat Variant. The Passat has been produced since 1974. The TDI version has been available since the early 1990s .

@Ulf
The altitude sensor is defective and providing nonsensical readings. It starts malfunctioning at speed x.
It resonates and ultimately makes no sense.

However, there's another possible explanation: it could be a very old 1Z.
In that case, the height sensor would have had to be located outside the MSTG, just like in the G3.
Then there's also the possibility of a resonance-induced intermittent connection in the wiring.
Question.

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

'lg' is an abbreviation for 'liebe Grüße,' which means 'best regards' or 'love.' It is often used in emails and letters to express affection or friendship.

Here is an example of how 'lg' might be used in a sentence:

'I hope you are doing well. lg, [Your Name]'

In this example, 'lg' is used to express affection and friendship. It is a way of saying 'I care about you' or 'I am thinking of you.'

Rudi wrote:

Quote: It's a Passat variant . The Passat has been produced since 1974. The TDI version has been available since the early 1990s .

- Sorry, the signature wasn't up-to-date yet.

MKB AHU, but only since the end of 96-00 - as stated above .

I'll adjust the measurement curves later today, after work.

Sure, here's the translation:

"Best regards," or "Sincerely,".
Jones.

Can't the height sensor simply be replaced with an external one with a little DIY work, or could the engine control unit (ECU) be mounted in a way that dampens vibrations if the problem is due to resonance?

MKB AHU but only since the end of 96-00 - as stated above
... My mistake.
Then it's definitely an EDC15 (new, approximately 1050 EUR) with an integrated sensor.

I would try to get a used STG (steering control unit) from eDings and replace the sensor.

@Bastion:
Externally, you can ignore it; damping probably won't help (anymore) since the baseline noise levels are already...
are wrong.

Best regards,
Rudi

Okay, then let's at least try to dampen the sound. If it works, we can postpone buying the silencer for now.

The 1Z/AHU control units are not very expensive on Schrottbay.

Okay,

Today, I conducted a new measurement. The altitude sensor gave the expected nonsensical readings. However, this stupid thing refused to go into emergency mode. It seems like it doesn't care.

The boost pressure curve actually looks quite good.
You can find the measurement file and the screenshots of the situations here:
http://jones1978.jo.funpic.de/vag-com/

At least now I have something to keep me busy this weekend.

*g
jones

Is this sensor really such a huge problem? I just can't imagine not getting it.
@jones1978 - Could you record a video when you start opening the MSTG?