I have a 0409 blink code on a '99 Max, which translates to a P0133, which I believe is "bank 1 upstream" (feel free to correct me).

Where is this sensor physically? Any tricks to replacing it? I have an Oxy Sensor socket but it has been in there a very long time (150L).

Thanks,

 

Physically it should be up on the firewall side of the engine right near your passenger cv axle about 3-4" down from the flange (going off memory). If you can't see it feel up along the passenger side of the y-pipe near the axle support bracket (should be just above the axle in that area), it's kind of hard to miss.

As for tricks, I haven't personally had to do them with the y-pipe on the car, but pb blaster should help a decent bit -- heat if it's real stubborn.

 

use a lot of PB be careful! i replaced mine today and broke the bung right out!

 

Bottom access only?

Is the bank2 sensor far enough away that I'll get the right one (bank1)? I have very little time working on this car... only done trivial stuff, so I have no idea of the layout of anything.

 

Bank two is in front of the motor at oil pan level, bank one is behind the motor at oil pan level. The downstream O2 (bank 1, sensor 2) is behind the cat between the driver and passenger seating locations. If you replace the one behind the engine, located on the downpipe you'll be good.

 

if you PB it and it still wont break loose soak the ever living crap out of it and blast the max around the block hardcore. then it should come loose.

i have an aftermarket y-pipe so i really dont remember where it was in the stock location.

 

Thanks all... I'll get to it.

 

Yep - get the Bank 1 sensor (bank against the firewall) from the bottom; much easier with a lift. My upstream sensors both came out w/o too much trouble; downstream sensor was a PITA - ended up needing to heat the bung almost red hot to get the sensor loose. And there is little worry about confusing the Bank 1 and Bank 2 sensors - Bank 2 is at the front of the engine compartment and easily accessed from above.