I have been having o2 problems as well. I can put new sensors on and the light still comes right back on. If i can get my hands on an obd-1 scanner what should I look for and do I need to look into getting a new tps??

 

Baraka, take a flat head screw driver to the side where the clip is towards the rear of the engine. Start trying to separate the diagnosis box first, then put the flat head in there and pry it open. Works like a charm and takes about 3 seconds.

 

Can you give me the link for the 'how to' change the O2 sensor you wrote up..thanks.

 

Hate to revive an ancient thread, but my 92 SC400 threw codes 21 and 28. I replaced both main o2 sensors yesterday and reset the ECU by pulling the EFI for 10+ min, but after a few minutes of driving, it threw codes 21 and 28 again. I see many people on here are having the same issue, but there are no solutions. Anyone that posted here before with said o2 codes, what did it take to fix it? How is the TPS related to codes 21 and 28? Thanks

 

Also to add, I have no running issues, the car pulls hard at all speeds, but I do have a high idle (1100 rpm)

 

Any update on your status or solution?

 

nope sorry. I'm going to get my Supra up and running before I divert any attention to the SC.

 

has anyone tried replacing or testing your knock sensors I ran test on mine today with a o scope and found irregularity in the pattern have ruff idle sometimes fuel smell from running rich even though it says its running lean in open loop (at Start up gettin to operating temp)

 

your right about the lean code but the universal o2 sensors wont work without modifacation i took the oem o2 sensor cut everything off the play then had to drill nd tap the threds for the universal sensor it was 40 bucks for the 2 upstream sensors then another 40 for the machining buying the replacements saves me 100 dollars but what i dont get is my car is running lean but it gross polluted on hydrocarbons but thats unburned fuel i believe

 

I just did the 2 mains with Denso O2's along with 2 high flow cats and I still have the lights on which code 21. I see someone did the actual code reader and got the TPS but when you did it yourself did you get the O2 sensor?

 

I changed and inspected all my spark plugs today, the white smoke was less and so was the gas fumes , i am gonna run a straight pipe after the resonator and replacing my front o2 sensors first cause my motor is lean and pushing more fuel , injectors will be tested and flush of the radiator and heater core , found a clean lexus at the salvage yard to pull parts off , ecu for $40 , grill for $30 ish , getting coil overs , used spacers on front to clear aftermarket rims from touching calipers, replace those wheel studs for longer ones, this eebsite/ discussion biard is very helpful

 

Do you have that by chance? I am trying to do the Bank 2 sensor 1 and do not want to take off the exhaust manifold