QuestionRe:1995 850 T5R have just completed replacement all vacuum hoses and connectors,egr and pcv hoses and connectors, and both 0xygen sensors (before and after cat converter) to pass California emissions inspection. Now getting three OBDII error messages which pop up after 40 miles or so after clearing codes: P1418 "Fuel level sensor circ signal too high", and two P0131 messages "O2 sensor circuit low voltage bank 1 sensor 1" and same message ending in "Sensor 2" Note: First tried universal generic replacement o2 sensors, got above messages, then tried new Bosch direct fit replacement for front sensor, but same error codes reeappear. Car is running well, full boost, smooth idle, smooth shifting, 23 mpg highway, despite error codes. Dealers are foaming at the mouth for me to bring in for service though they won't discuss likely repair costs.
Any Suggestions on how I can troubleshoot?
Answer Lee, more than likely you have connector problems. Be sure you have a direct fit Bosch in the rear as well. As you have learned, Bosch systems are very "fussy" about their O2 signals. Clean connectors and rechek for vacuum leaks. Also be sure to check for any kind of exhaust system leak. Use a high quality contact claeaner/oxidation remover spray on both ends of the connectors.
If all this fails, then I would want to see what voltages the sensors are actually reporting. If they are indeed low, then one of two things. Too much air is entering the system or not enough fuel is being delivered. The first usually a vacuum leak and the second can be complex. First I would want to look at the injector wave forms, on times especially. If low, look at CTS (coolant temperature sensor) voltages first. If ok, I would look at the air mass meter next. Very, very seldom the air mass meter is causing problems unless you have aftermarket air induction systems installed. Read K&N fiters. The oil used in them can contaminate the platinum wire in the air mass and deliver faulty readings.
It must be a very small discrepency because your mileage #s are good and no detectable performance problems.
My only other thought is that the kitty cat might be going bye bye?
Mark
