Replace exhaust sensor 1 (G235) in the 9N3 BMS

Dear community,

"I have a Polo 9N3 from the year of manufacture 2007 with 194,000 km, engine code BMS, and an interesting fault pattern where the vehicle temporarily (from 1-2 seconds to up to a minute) has effectively 0% power. This happens suddenly and disappears again within a second, allowing normal driving. The error memory indicates that the exhaust sensor before the turbocharger is not functioning correctly."
A test run confirms a short circuit to the positive terminal for G235, resulting in an exhaust gas temperature of 930 degrees Celsius when the error is "active," both during driving and at idle. Otherwise, the readings are mostly random and implausible.

Unfortunately, in the repair manual for the BMS motor, I only see an exploded diagram and no detailed textual instructions on how to replace the G235 component.

Since I don't have permanent access to a lift: Does anyone happen to know if the G235 can be replaced without removing the turbocharger or DPF?

Best regards,
Maximilian.

Hello,

The temperature sensors should be replaceable without removing the turbocharger.

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

"LG" translates to "Best regards" or "Sincerely" in English. It is a common abbreviation used at the end of emails and letters.

Hello, the sensor can be replaced relatively easily from below, through what I call the "transmission tunnel." However, in my opinion, it's impossible to replace it from above. Removing the turbocharger is not necessary.

Hello everyone,

I can report that the sensor replacement was successfully carried out through the gearbox tunnel.
Now the sensor is providing plausible values. The actual error (100% power loss) still occurs, but much less frequently than before.
Unfortunately, I haven't been able to "catch" the phenomenon during new test drives yet, so I can't say for sure whether the cable to the control module (MSG) might also be a problem in addition to the definitely defective sensor (which would be quite a strange coincidence), or whether I need to look for another cause.


Best regards,
Maximilian.

A badger got into my car and chewed on something... That's why you should check the cable at the same time when replacing the sensor.