maxpower10

I just bought a C320 4Matic with 90,000 miles on it. I noticed a ticking noise at idle. It gets faster as you accelerate and stays regardless of engine temperature. It sounds very much like a sticky lifter but does not go away. It is very noticeable but I would not consider it a knock so much as a tick.

Shortly after leaving the dealership (3 hour drive at 70mph) I slowed to about 35 mph. Just as I slowed the check engine light came on. I did fill up with premium (91 octane) fuel and was very careful about tightening the fuel cap. I tried starting the engine 4 times in a row as stated in the manual but the light remains on. I'm wondering if this could be related to the ticking noise.

The other thing I noticed was a considerable amount of road noise. Seems like a whirring noise from wheel bearings but I've never owned an AWD vehicle before so I'm wondering if the drivetrain is just going to be that lound.

Thanks in advance!

Akhafeez

Did you open your engine while your car is on? I had a similar noise, turned out to be a water pump failure. Start your car and open the engine, see if you can see anything

maxpower10

Visual inspection showed nothing. Sounds like its coming from the left side of the engine though.

maxpower10

I just started it up after it sat in 6o degree fahrenheit weather for 20 hours and no noise at all. I didn't have time to drive it but I'm assuming it will come back when the engine warms up. The electronic oil level checked just fine.

phister

get the CEL pulled from a parts store since they do it for free. Buy some techron fuel cleaner and toss some in the next fill up to clean up the fuel system if the previous owner never used it.

maxpower10

here are the codes

PO432
Main Catalyst Efficiency Below Threshold (Bank 2)

PO422
Main Catalyst Efficiency Below Threshold (Bank 1)