pcar928sg

I'm looking at buying a 2001 Sl500 with 66K on it and the car is in perfect condition. The it runs and drives fine, but the check engine light is on. I used an ODB2 scanner and it showed codes for all 4 Oxygen Sensors being bad. The owner is an older gentleman and his wife was the primary driver and so he doesn't know how long the check engine light has been on. The car is located in a state that doesn't do car inspections, so it could have been on for years.


I find it odd that all 4 would show as bad.


I have access to parts at wholesale so Getting 4 Oxygen sensors isn't that big of a deal, however I don't want to just throw parts at it if something else could have caused the errors. ie, maf issues or the like.


Any suggestions?

cliffyk

What exactly are the codes?

The O2 sensor heaters share a common power source, fuses would be the first thing I'd check however the actual power seems to be channelled through the base module at pin 18--I cannot find what the source for that is,,,

pcar928sg

Tonight we reset the codes and after starting the car and backing it out of the garage the check engine light came back on. Upon checking the codes I'm only seeing the following:


P0150 - 02 Sensor Circuit Malfunction (Bank 2 Sensor 1)
P0155 - 02 Sensor Heater Circuit Malfunction (Bank 2 Sensor 1)
P0156 - 02 Sensor Circuit Malfunction (Bank 2 Sensor 2)


So now it appears to only be on one bank.. Bank 2 is the passenger side right?

cliffyk

Bank 2 is the left, driver's side on a LHD vehicle...