PO131 O2 sensor low voltage

[Lee86]

Hi, I had a PO131 code pop up on ML250. I’m no mechanic so wasn’t planning on going to far in depth myself, but I checked under bonnet and noticed since my service last month the Oil dipstick had been left out slightly and oil has been coming out. It’s been leaking over the engine cover then seeping down onto the ECU. I took ECU out and checked cables and Connectors and there wasn’t any oil in them. I have now cleared the code and waiting to see if it returns. But I’m wondering if there’s anythin else I could check that could be causing the code or where the oil could have collected. Thanks

 

[onefortheroad]

Chances are the O2 is knackered,it's not uncommon issue.

 

[Lee86]

Had it replaced at Mercedes 3 years ago, around 20,000 miles ago. Surly they should last longer than that??
Seems a big coincidence this only started after this oil leak. Could oil make its way as far as the bank 1 sensor?