Oxygen Sensor Part Number and Location

[timbo1]

2003 Sequoia 2WD. CEL and VSC lights on. Went to Autozone, was told Bank 2 Sensor 1 was bad. I purchased a Bosch sensor, part # 13624. Removed sensor on passenger side(under seat area...was told this is sensor location), replaced with new sensor. Old sensor does not have hex nut; new one does. Installed replacement. Lights went out, but came on again 10 minutes later, and have been on since. Went to Advance Auto, was told again Bank 2 Sensor 1 bad.

I have either (1) the wrong sensor; (2) a defective sensor; or (3) did not replace the correct (bad) sensor. Need to know: Is Bank 2 Sensor 1 the sensor under passenger seat? Any inputs or suggestions will be appreciated.

Thanks

[boatbuilder]

nope. Bank 2 sensor one is the sensor up the pipe towards the engine. There are two per side. they are numbered from the engine back. You are going to have fun with that one. It took me 4 hours to get the driver side sensor one out. It ended up breaking off and ruining the threads in the pipe. Took forever to find the correct tap to repair. After you get it changed, you will still need to have the codes cleared, or unhook your battery.

[timbo1]

Thanks for the info! I'll let you know how the replacement goes.

[jliltd]

My 2001 2WD Sequoia MIL (Check Engine Light) has been lit for two years. Always got the same answer every time I had dealer check it out. Young punk newbie service techs always told me I needed all new catalytic converters and oxygen sensors for around $2,000. When I would ask why they would always say the diagnostics said so ($89 diagnostic fee with no real physical inspection or experience-based knowledge). I knew they were wrong (catalytic converters should last a couple of hundred thousand miles at least).

The other day I had the Sequoia down to install trailer brake controller and a 7-pin trailer plug. I saw Autozone had a $39 ODBII computer scanner at so I bought it and re-checked codes (420, 430 etc..) The OBDII codes (B4 and after new scanner) were always emissions related. Finally decided to do it myself by installing all new oxygen sensors (4), consisting of two new Toyota (Denso) OEM after-cat oxygen sensors (p/n 8946509300) (bank 2) and two new Denso before-cat oxygen sensors (p/n 234-4209) (bank 1). Also installed all new Denso PK20R8 double-platinum spark plugs (p/n 3127) (.032 gap). Toyota OEM Bank 2 sensors bought from Autonation (Parts.com). Spark plugs and Bank 1 sensors bought from sparkplugs.com. Total cost of sensors was around $250 for both sets. Same parts at local dealer would have approached $700. The non-OEM pre-cat versions required plug splicing (wire colors all match) but no big deal. Looked identical to removed OEM versions (Denso). I steered away from Bosch products and stuck to Denso (like Toyota does) after reading posts here on TS.

The Denso replacements from Sparkplugs.com came with copper anti-seize compound and it only took about 1/2 a tube to apply to both pre-cat sensor threads and 8 spark plug threads. Rear sensors use gaskets and don't thread in so no anti-seize used there. Still have a whole tube unopened left over. Be careful to not get any anti-seize compound near the business end of things to avoid fouling of the component (I always apply up to but not past the first two threads to make sure).

I borrowed a O2 sensor removal kit from Autozone (deposit required). I also sprayed all old sensors with PB Blaster penetrant the day before (Kroil penetrant would be as good or better). I was stunned how easily it was to remove the front sensors from the threaded bungs. The electrical plugs were actually harder. The front sensors that re-used the spliced original electrical plugs snapped right in to the chasis electrical recepticles nicely. I did find the rear after-cat Toyota OEM replacement sensors hard to plug back in to the chasis electrical harness. I fished the red silicon gaskets out of the chasis recepticles and shaved one segment off them with a razor blade and then reinstalled them. Then the new rear sensor plugs snapped in without a problem.

Added 2 bottles of Chevron Techron fuel additive to fuel tank and filled tank with premium fuel (have the common sticking fuel sender problem). Cleared diagnostics codes related to emissions with the ODBII scanner. After 1,000 miles including towing MIL does not light. Mileage and power have improved and engine runs like a sewing machine and fuel gauge behaves (due to Techron, not other work).

P.S. The only reason Toyota uses two part numbers for the OEM pre-cat sensors is due to difference in wire lengths. Not an issue when splicing your own. I left a little extra length in the spliced harness assemblies for future servicing. I also cut off and kept the plugs from the after-cat original sensors and stored them away in case I ever need them.

[jadetundra48]

do you recall what size nuts that fasten the after-cat sensor

[jliltd]

I'm not sure the physical nut size but I think it's a 10mm metric socket that does the job. They're real easy to see under the truck, right between the front seat and rear seat passengers. They have a metal heat shield held in place by the same nuts. It seems about 90% of the nuts and bolts used in common light maintenance for Toyotas are 10mm wrench size (i.e. dash bolts, ground wire screws, rear oxygen sensor clamps, most body bolts). There are occasional 12mm and 14mm when you move up to oil changes and skid plates. The front Oxygen sensors are 22mm and the spark plugs are standard 5/8" socket.

[bdeason]

Can you tell me what the wire colors are for bank 1 sensor 1 and bank 2 sensor 1 (upstream O2 sensors). I'm in the process of installing an EFIE. Specifically, I need to know which wire is the O2 sensor signal wire(s).

Thanks for the help!

Bob

[jliltd]

I don't know the color coding. There must be some universal standard because all that has to be done is to match the wire colors and splice. I don't know which color is what, just that the colors match and everything works like new now.