Hello everyone,

Today my check engine light came on and I pulled into Auto Zone to see what codes were present. I have a 1999 ML-320.

The following two codes were present

1. P0161
2. P0442

P0161

OEM Brand:OBDII
The PCM has determined that a malfunction exists in the heater circuit for oxygen sensor 2 in bank 2. (Oxygen sensor 1 is closet to the cylinder head before the catalytic converter, while oxygen sensors 2 & 3 are located further downstream and are typically mounted in or after the catalytic converter) (bank 1 identifies the location of cylinder #1, while bank 2 identifies the cylinder on the oppositer bank)

P0442
OEM Brand: OBDII

The PCM has determined that a small leak exists in the evaporation emission control system

I would like to know how serious of a problem I have on my hands. As for myself I think this is nothing more that a defective oxygen sensor and fuel cap not being tight enough.

Anyway, any suggestions are appreciated and if advice is given to buy something please provide the web site url so I know where to go to order and/or review.

Thank you everyone for helping me.