MercedesFam

Hi everyone!

2001 CLK 430
Mileage: 207,691

Codes P0150, P0155, P0300

Check engine light was on and had to get it ready for smog in Arizona. Replaced the Oxygen Sensors(Upstream) both, brand new OEM EGR valve, Cleaned the 'accordion' tube, new MAF sensor and seafoam treatment. Not much white smoke but car was running supreme for that Saturday last weekend. Check engine light came off by itself and I passed emissions with ease. An hour later the Check engine light came back on but car was still running superb.

Long story short, it's the wife's car. This thing was running superbly. This weekend, it is running like s!@#. Took it to Autozone and they gave me these codes and O'reilly gave me the same ones as well.

I'm really up in the air with exactly what's going on with this car. Before going to Autozone, I punched the gas and was flying but 5 seconds into gassing it I let go and the engine felt like it dropped out of the car. I'm fairly good with DIY and would rather knock this out myself before giving up and shelling out to the dealer.

The codes mention the oxygen sensors, what are the recommended oxygen sensors to buy for this car?

P0300 mentions the ignition system and fault with spark plugs and ignition wires and maybe the coil? Can someone help me understand this?

Was told there might be a vacuum leak or injector fault with this and also maybe high or low fuel pressure?

I like this coupe and its been good so i am hoping for some decent if not great advice and if anyone here can please point me in the right direction with steps in the process of elimination with bringing 'her' back to life.

It would be very much appreciated....

Thank you in advance!

miatawnt2b

what are thw new codes? sounds like a TPS, but we need to know what the new codes are. have the old ones cleared first though.

MercedesFam

Thanks miatawn2b for your response.

Those are the new codes. The previous codes was in regards to the EGR valve and Oxygen Sensors, but those were cleared and the CEL went off. Yesterday both Autozone and O'Reilly gave me these codes:

P0150
P0155
P0300

These weren't showing up at all last week. Now they are and the car is running real sluggish. Trying to do the process of elimination before throwing brand new parts galore at it. TPS? Throttle position sensor? No codes showed up in regards to that. This all started after replacing the MAF and EGR valve. Maybe the system has built up somewhere?

miatawnt2b

It sounds like the codes weren't really cleared. The CEL can go off by itself once the fault is no longer detected, but the codes will still be in the ECU. Additionally, my TPS went out and It took 3-4 times of restarting the car and hitting WOT (wide open throttle) before the TPS code was stored in the computer.

Anyhow, as to your symptoms now, does your car run fine when you first start to drive and after you hit WOT there is no throttle response until you turn the car back off/on again?

I would take the car to the parts store and ask them to completely clear all codes. Then see what pops back up.

-J