Audi A4: Sudden Power Loss (Pierburg MAF Sensor)

Hello everyone,

"Yesterday, something strange happened to me. After overtaking a car, I suddenly lost all power. The engine was still running, but it didn't go into limp mode. It just didn't have any power. I initially thought it might be related to the VTG (Variable Turbine Geometry) and its adjustment, as I had recently replaced the hose to the vacuum actuator because it was worn. I then drove home like that. When I got home, I restarted the engine briefly, and to my surprise, everything was back to normal. This morning, I read the error codes."

16485 Air mass meter G70, implausible signal, error code P0101, -35-10---, interrupted.
17958 Boost pressure control differential p1550-35-00.

After that, I cleaned the mass airflow sensor and took it for a test drive. Still no power. I observed the boost pressure during the drive (using VAG-COM). Well, if you give it short bursts of acceleration, it does go up to 1 bar, but when driving normally, it only reaches 0.4 bar at 2500 RPM.

After that, I cleared the error codes and restarted the engine.

Unfortunately, the error persists.

17552 Air mass sensor G70: Disconnection/short circuit to ground detected.

I checked the connector, and I didn't see any broken wires.

I have to mention that the mass airflow sensor (MAF) doesn't seem to be original. It was replaced by the previous owner. I believe it should be a Bosch part, but I have a Pierburg one installed.
However, I drove 80,000 km with the Pierburg unit and only had to clean it once.

Can I check if the LMM is still producing reasonable values before I consider buying a new one?

Regards,

Thomas.

/viewtopic.php?t=20765&highlight=pin assignment+MAF

Only measuring helps.

Best regards, Rainer.

"Since it already has a Pierburg mass airflow sensor, it should be fine as is."

I logged data blocks 08 and 11 today.
Unfortunately, I was unable to create a visually appealing diagram.

Here's the translation:

"I also need to mention that the AGR (Abgasrückführung - exhaust gas recirculation) system is deactivated. After restarting the engine, and initially when starting to drive, nothing happens. However, if you fully depress the accelerator pedal in first gear, there's a surge at around 2500 RPM. I think that's when the VTG (variable turbine geometry) unlocks."

Today, I sat down with my laptop next to the car again to see if it was really the mass airflow sensor.

I believe the LMM values are written to measurement block 3.

I think field 2 shows the target value, and field 3 shows the actual value.

In field 3, there's absolutely no activity; it's stuck at 550 mg/r, regardless of the speed.

That's why I'll also notice the increased fuel consumption, as I still have to drive the car every day.

And after 2200 revolutions, not much more happens.

Am I right in assuming that the mass airflow sensor (MAF) is defective?

Today, I measured the pin configuration of the mass airflow sensor (MAF) with the engine off. Everything seemed okay, except that one pin, which should have had 5 volts, was showing slightly over 7 volts.

Is that something to be ignored?

Regards,

Thomas.

Quote:

Is that something to be disregarded??

No. It's likely a measurement error or a faulty wiring harness. The voltage regulator is less likely the cause, as that would also affect all other sensors, which would then receive 7V instead of 5V.

Hello.

I installed a different LLM, and that was the problem.
As I found out from this forum, the Mercedes Sprinter now has a Bosch system again.

I actually have one more question: When the engine is idling, I'm getting a reading of 440 mg/h, which is quite a bit different from the target value (250 mg/h).

Is this still normal?

Regards,

Thomas.

Quote:

I actually have one more question: When the engine is idling, I'm getting a reading of 440 mg/h, which is quite a bit different from the target value (250 mg/h). Is this still normal?

Therefore.

Quote:

What I still need to mention is that the EGR system is deactivated.

is it "normal"?

Best regards, Klaus.

Yes, that's right, I could have figured that out myself.
Thank you again to everyone who helped me.

Regards,

Thomas.