DaisyDrift

That is a really thoughtful reply. I am really appreciative. Throughout are a few excellent pieces of advice. There are 127,000 miles on the vehicle. It is a 2010 model year. Instead of a service book, it just includes a few haphazard receipts. It appears that the air filter has been neglected for a while, given its state and the number of unresolved issues.

These will fall if the panel is removed carelessly. Here, YouTube is great. I can rebuild it, but it's going to be a real pain. You may find new replacement panels on eBay. While it's out, change the bulbs in the back; that's probably why someone took it apart and destroyed it.

https://www.ebay.co.uk/itm/116870869553?fits=Car+Make:Mercedes-Benz&_trkparms=amclksrc=ITM&aid=1110006&algo=HOMESPLICE.SIM&ao=1&asc=20240415110138&meid=f7fcd442dd2441cebd1b7a3adaba7861&pid=101875&rk=4&rkt=4&sd=335543581674&itm=116870869553&pmt=1&noa=0&pg=2332490&algv=SimplAMLv11PairwiseFitmentPromotionV2WithCassiniQueryEmbRecallKatReco&brand=Trucktec+Automotive&_trksid=p2332490.c101875.m1851&itmprp=cksum:116870869553f7fcd442dd2441cebd1b7a3adaba7861|enc:AQAKAAABYCggmqi%2BjGBvS8WShKTeLW5J2g6qXnzgH61T5t8ujPfO4ZJHWSDajmSreRV%2BXNto1elxKNVVM64kNmwVgiMN2szhK0tlR1011FXMzSAB1PUgv3YfSpR1rhptekHpigLfP0ecJgwNe2pRkmfW%2B3c3dKMszZ8EBS%2BPrP%2F9xIMfOGg7iuIfw%2FFDuxCGlnZ7D3zgzTgy9DT4%2FS1LGPGydF%2BKwF9lTD7jlYVT7xPKhGqy39hGE8w8PJvaKk06XNzpIlaFQu7Pc2PhpPC%2FLZ4ZS5Fd%2BVmYjS4Sycj9rg7mxJCIClaeI9XvAYQ%2F9jfg6eilx1CW22rnBYhd%2Fz2GfmcyXT7cQwfU0jXVQdGQdI%2FRE%2Be3aRYEsbp1kEtV9d%2FFS1mpu9AQnqnAyIjyxNroh%2FB5QDBHL6s7W7WvO9VZmi0JXErPzjVzJ7m%2BmyLBAoAtkTsH5hEFQSiSXh6iA%2Bi1fIHQW%2F5uNW8%3D|ampid:PL_CLK|clp:2332490&epid=1027347547&itmmeta=01KB82JK0KBBGW9XAV4JNHE8N2&mkevt=1&mkcid=1&mkrid=710-53481-19255-0&campid=5338181125&toolid=10001&customid=2518X1570512X22d8b1553c31b0acceae4be1fe8d7448&subId2=15

I don't know what you mean, but I would check the wiring leading to the engine control unit (pilot bush). The 'o' rings are movable.

After giving the seal a thorough washing with white spirit, I proceeded to run a bead of silicon across its inside and exterior. On occasion, I would check for signs of seepage by running a white tissue beneath the turbo connect.

“Why” is the key point. Other points made thereafter, nevertheless, may provide light.

A creeping mission! There will be a complete fluid change and the cost that goes along with it. You should rethink the first idea if the leak isn't severe and if you don't have a lot of emotional investment in the car. Simply add more and watch the results unfold. Note that the initial fluid loss could be substantial if the fluid is draining or leaking to the level of the leak. If you had half a litre of fluid and a plastic funnel, you'd be able to tell which way to jump.

Where is the missing oil? That's the query that came to mind. I guess it depends on how bad the leak is if it needs fixing.

That isn't the hard part. Instructions will accompany any info that deals with checking the level - handbook?

There are two advantages if a drain plug is available. Before you add new oil, remove the old, worn-out fluid. Then, use the torque converter volume as a reference to determine the fill quantity. But that's only true if the drain is plugged in.

So, you're not "big on skills," huh? Is it possible to remove the current fluid using the drain plug? Just because...

There is typically a predetermined order to inspect the levels in an automatic gearbox, such as checking the temperature and manually shifting gears. If you know someone who is experienced with this model, they can provide advice.

The large pulsation damper is responsible for the spikes that activate the light. Just to be safe, I'd swap everything out, then properly bleed the system before the rodeo.

That may occur if the system contains air or if the valves are not operating properly, leading to the reservoir being overfilled with pressure.

An ABC problem exists if CHF11S is present in an unexpected place. Verify that the system has been adequately bled before opening it.