Fuel problem in my '98 E320
Fuel Injection Clean Up: 1/2 of a $9 bottle of Stabil Marine Fuel Stabilizer on a full tank... follow with the 2nd 1/2 bottle about 5-6 tankfuls later (like 2500 miles or so).
Flashing CEL Light - download a 98/99/2000 E-Class owners manual from MBUSA.com Owners Section - and YES get codes read from generic OBD reader and poist here.
Keep the beat !
You do need your generic "codes" read and report here...
In the future - again best to check forum 1st - in this case you don't want to start adding fuel additive #2 on top of fuel additive #1 - frankly there are several advantages to Stabil Marine - including it helps clean-up the in-tank fuel level sensor - things like that to best spend under $10 for the "best" injection cleanup with Stabil Marine/Blue..
P0150 - Oxygen Sensor 2 Malfunction
P0155 - Oxygen Sensor 2 Heater Circuit Malfunction
P0173 - Fuel Trim Malfunction
P0300 - Random Misfire Detected
P0304 - Cylinder 4 Misfire Detected
P0305 - Cylinder 5 Misfire Detected
P0422 - Three Way Catalyst (Right) Efficiency Below Threshold
P0455 - Evaporative Emission Control System Leak Detected (Large Leak)



