Hermann MHC-218

Hello!
I know its a german forum, i hope its ok to write in english though?
I just bought this Gastester MHC-218, and have a few issues with it. I noticed there are some experts on this forum that may be able to help?
So one thing, i get all other values on the measurement, but on O2 and lambda i get dashes --.-- . Maybe i have an issue with the oxygen sensor, and if so where it is located?
Other thing, other values seem to show correctly, but HC is too high (about 100ppm too much at idle), compared to values on the same car on inspection.
And also, when i run the leak test it shows "not passed".. Can this be related to the oxygen or hc values..?
Thanks in advance!

Ville

…i fear someone manipulated a lot on this Tester, usualy you dont get into the messurement Programm if the O2 Sensor is worn or the leak Test isnt successfull ! 

Hi,

oxygen sensor is behind a lid on back right side. Normally this tester makes a selftest before it starts including oxygen sensor, pressure sensor and gas measuring bench. You should see those tests being performed before it starts. If one test fails it shall not start.

Yeah, it actually does the selftest and passes all the tests in the start screen. But if i run the leak test through the menu it fails. Hard to say if someone did something to bypass the tests.
But i recall the previous owner stating that the O2 and lambda was still working when he used it the last time..
Thanks, i will check the oxygen sensor. Can i test it somehow to confirm its failed?
Also does anyone know where i could get parts or calibration gas for it?
Thanks for the help!

Hi Ville,

if measuring test bench does not pass leak test, it should also not continue. Check the rubber hoses inside if they are leaking. Also cleaning with water can help. There is a special procedure in manual how to do that.

Ok, thanks Dr-DJet for the info. Will open up the unit today to check.
Unfortunately, i don't have a manual for it. Do you know where i could download or buy one..?

Hi,

I have never seen a manual in English. You can try with AVL or maybe with our user Pagodefan1970 .

Yeah, ok. Well i don't mind if it was in german, i will use translate if necessary.
Ok, thanks i will ask him.
Oh, and actually i did open it up and cleaned the oxygen sensor. Didn't help and still shows just dashes.. The weird thing is, it still gets through the selftest, even with oxygen sensor unplugged.

Ok, just wanted to update. I replaced the oxygen sensor with a new one from ebay, and all values now work!
So it looks like it was just a bad sensor, weird thing it would still pass the tests.. I'm thinking maybe someone altered the programming at some point to make it pass even with faults.