ShaneN.

First off, I'm running amercian racing headers/catless x pipe and I got a p0056 code today. I remember reading that it's common to fry 02 sensors when you do headers, but I believe that was the upstream sensors, (17016) correct? Based on that previous research I did two new 17016 sensors right away when I got my car back from getting headers installed and before throwing it on the dyno.

However, the p0056 that is downstream sensor drivers side which would be part number "bosch 16749" i think? Which is NOT one of the sensors that people have issues with after doing headers? Should I replace these downstream sensors in pairs? And was I wrong to have thought that the EC V7 tune would have shut these off since I have no cats?

And finally, the plugs for the upstream and downstream are opposite judging by pics, one is male(07016) and one is female(16749), so there is no way that the guy that installed my 17016 back then could have put them in the wrong spot (I just remember him saying they were easy to get to at the time)?

ShaneN.

I was all over the place and confused so I edited it to hopefully make more sense.

chrisridebike8

I had a code for the downstream sensors at some point. One of the heater circuits failed. ARH LTHs and EC v6 header tune. The tune shuts off the rear sensors but for some reason they still need good sensors plugged in. I replaced both and the CEL went away. I used the bosch plug and play replacements.

ShaneN.

Interesting, I guess I'll see who has them locally cheapest. Hopefully it isn't going to affect anything to use the car while I search for the sensors tomorrow?

ShaneN.

Literally every store in Canada I call can't get them and they're on back order. Mercedes has some on the other side of the country and they want 1.25x the price that they sell for. Does anyone see any problem using the NGK/NTK 25186? It's supposed to be the equivalent.

MBNRG

You are correct, the Upstream (Primary) O2s are Wideband, and will have more wires, hence the plug is 6 prong male (i believe).
The Downstream (Secondary) O2s are simply oxygen sensors (without Wideband function), and their plug should be female with 4 wires.
These Downstream O2s have MB Part #: 0045420718 (Bosch 16749, confirmed on Bosch website) - the same part for both Right & Left orientations, and should work on both FL and PFL models (i believe)

Eurocharged cannot completely code out the Downstream (Secondary) O2s - my understanding is that their O2 sensing function is turned off, but their Heater circuit remains intact.

Amazon Canada shows 6 in stock

ShaneN.

Solid info thanks. I saw them on amazon but the quickest I could have them shipped is Friday which won't give me much time to get them installed before a cruise I'm going to that eve. I ended up grabbing two NGK/NTK 25186 which are SUPPOSED to be compatible for 85cad each. Mercedes wanted $212 and for it to ship from Toronto.