Just put on a y pipe on my 2001 Max (wifes car) she said he SES was on so i pulled codes tonight. dont remember exactly what they were but p0135 p0155 p0171 etc etc all O2 related bank one and bank 2 i could see bank one being bad but not really so much for bank 2 esp all at once... any ideas?

is there a fuse location? i wasnt able to find a fuse

 

Any drivability difference ?

 

Fed or Cali emissions? Did the y-pipe replace the pre-cat(s)?

 

2001 cali (all 01 are cali from what ive read)
replaced bank 1 cats not bank 2 but still had codes for bank 2 O2s

no drivabillity difference and no major loss in mpg... she got about 350 mixed driving

 

any tips on removing the o2 harnsses? they clips of the o2s have those teal pita things to push down. never had any of them on my 4th gens ill take a pic tomorrow if need be

 

Usually, the O2 sensors codes don't affect mileage enough to really notice. Especially after only one tank. I would reset them and go from there. Often with OBDII, codes will cascade. It doesn't necessarily mean that you have multiple isolated problems, but just that the system has a problem. You may end up having to use an O2 simulator after the pre-cat delete.

I have an 2002 which has the O2 connectors mounted between the exhaust manifold and the radiator. You can insert a small flathead or pick to release the clip. Pushing the connector together first usually helps to get it moving if it hasn't been released in awhile.

 

Alright ill give it a shot. The 5th gens seem so much more finicky than the 4ths. I have no cats on my 95 and no codes haha. Ill pro. Do an O2 sim

 

Also shes been getting about 20-22 mixed in traffic with a heavy foot but shes been putting in 89 octane

 

O2 sensors do change over time. They will impact your MPG and eventually throw a code. Not sure if those are OEM O2 original, but if so, it is time to change them. You can gain a few more MPG if you do so. It is value sort of thing...if you value the MPG over the $300 for new O2 sensors then do it.

However, you can try the ECU reset and see what happens.

 

Reset the ecu and 8 of the 10 codes came back one i may just do o2 sims

 

Check your O2 sensor fuse located in the fusebox to the left of the steering wheel. If it's blown then perhaps one of your O2 sensors have exposed wire which is grounding them out on something.

 

Ok here's one answer in case you didn't know. Most Aftermarket Y-Pipes move the rear O2 sensor forward. The Bank 1 post-cat O2 sensor's job is to tell you if the Pre-Cat on Bank 1 is bad.

Most aftermarket Y-Pipes eliminate the Bank 1 Pre-cat on the 2001. So the O2 sensor gets moved toward the other pre-cat, this way, it actually monitors the front cat.

So you have two O2 sensors monitoring one cat, if that cat goes bad, both sensors with throw codes.

 

I have no cats and no pre-cat codes.

 

^ Yeah but you're cheating

 

i may just do O2 sims...the SES doesnt bother my wife but it bothers me

 

Since nobody has suggested the obvious, check your ground connections. A bad ground would lead to precisely the type of problems that you are having.

 

Nope, if you mean sims, nope, never used sims either.

 

Any ground wire or specific ines?