Fault code P0450, 97 S320 - PeachParts Mercedes-Benz Forum

ljackson3 · #1 06-09-2008, 06:57 PM

Hi Guys,

While traveling at highway speed, 80mph my car suddenly startedd running rough (light too rich). After reaching my dstination i pulled the code, P0450 (EVAP Emission Control System Pres Sensor Fault ).

Any idea of possible failure? I search the site but only found 1 instance referencing this code.

Urgently need help sice i commute 84 miles daily to work.

thanks

ljackson3 · #2 06-09-2008, 07:15 PM

holding my palm close to the exuast, i get a very distintive smell, close to rich mixture and collant. Also a distintive coating on the palm and a hint of white smoke.

Any ideas?

jw46 · #3 06-09-2008, 10:27 PM

hmmm. head gasket?.. not sure... will let the pro's diagnose this.. coolant smell and white vapor doesn't sound good...

jw46 · #4 06-09-2008, 10:31 PM

Quote:

Originally Posted by ljackson3

holding my palm close to the exuast, i get a very distintive smell, close to rich mixture and collant. Also a distintive coating on the palm and a hint of white smoke.

Any ideas?

Is there water in the oil, or oil in your coolant tank?

ljackson3 · #5 06-10-2008, 05:51 AM

no water in oil or oil in the water.... water level and oil are okay

mbdoc · #6 06-10-2008, 08:09 AM

100% not related to any running problem. That is related to the car retaining all of the fuel vapors in the tank.

Almost always related to an electrical malfunction of the fuel tank pressure/vacuum sensor. That sensor is part of the fuel tank sending unit.

ljackson3 · #7 06-10-2008, 09:16 AM

Thanks M.B. Doc, is there any test that can performed to validate before i pull the sending unit? Also, can you purchhase the sensor separate?

ljackson3 · #8 06-10-2008, 09:29 AM

M.B. Doc, I had a local mb machanic use his CS2000 scanner on the car and his recomendadtion is replacement of the coil for cylinder #1 & 6. We pulledd the plug on one and it was wet (fuel) indication of not firing.

any way to validate the sensor or the coil?

thanks

ljackson3 · #9 06-12-2008, 05:21 AM

Okay, I have replaced spark plugs wires, plugs and 1 coil (identified by CS2000 indicating plugs 1 & 6 not firing) but basic problem still exisit, hard miss. Also tried mocing the new coil to the other location with no change.

I am taking it back to the local mb shop..... any idea?

ljackson3 · #10 06-16-2008, 12:03 PM

After $600+ of dealer work, i think the basic problem is still there. Dealer diagnosed and replaced coil, wires and plugs. Also indicated possible injector issue which were addressed through cleaner. I have run the for over 6 hours while using Seafoam in the tank (2 cans for 25 gallons plus a third can at the next fill up of 27gals).

The car runs great at highway speed, performance appears to be 100%. At stand still it still has a hard miss. Is there something else we are missing (btw no codes or no check engine light)?