<duplicate thread: initially posted in Engine Management, but probably belongs here. I'll try to get a mod to kill the first thread before anyone responds.>
Evenin'. I have a problem. Well, technically I have two problems: a low AND high voltage on a brand new rear o2 sensor at the same time. How the crap?
My poor 04 ts recently destroyed (& clogged) its stock cat section, so I thought it would be a grand time to start upgrading.
I did what I could afford for now: the front half and a decent tune-up (hey, something had to blow up the old cat...).
Borla UEL headers
new gaskets everywhere (of course)
NGK BKR5EIX-11's (turns out you CAN spend over $8 a plug
New o2 sensors: (cooked the old ones when the old cat started to clog)
AFR: Denso 234-9015
rear: Denso 234-4706
Rallitek rear o2 spacer
...and then I sent it all off to the shop. (I live in a crap apt. with no space for tools and no access to a lift
Long story short, all of it bolted together perfectly, until the damned car turned out to have its "rear" o2 sensor 3 inches behind its "front" AFR, both in the front cat of the catalytic subsection. The Stromung HFC has the 1st cat deleted, and the rear o2 bung where it should be: in the rear cat. The wire on my replacement rear o2 was WAY too short to connect it to the harness, so I called up Caspers to order the harness extension...
...and they overnighted me one with the wrong *#&^!ing ends. $46 in shipping and it was wrong, wrong, wrong. This is probably my bad, but to be fair, it was labeled "Subaru O2 Extension Harness." Le sigh.
The shop picked up some decent wire, some ends, and some shrinky-dink tubing and spliced the rear o2 themselves, and I drove off a happy man...
...until it threw 2 codes a few minutes afterward: p0137 AND p0138. Together. How can my sensor throw a low and a high voltage at the same time?! Is it spliced incorrectly, is it a defective sensor, or did moving it back that far from its original location completely freak my ECU out?
Does an '04 EJ251 even use that sensor for its fuel trims, etc.?
Who the crap puts a downstream sensor 3 inches from the upstream sensor? That's retarded.
I'm open to suggestions at this point.