thoff

iTrader: (1)

Okay I have seen a couple of threads dealing with this, but I am puzzled to no end.... I have a 92 SC300 and I am getting Code 27 (sub-O2) however there is NO/NO sub-O2. I only have the two one wire O2 sensors that are located on the exhaust manifold. I have the dealer's manual and states that Code 27 is for the Sub-O2 (USA Spec) car. The sticker inside my door says Made in Japan. I also have another car that is the same way (no code however). I have replaced the O2 Sensors TWICE and I have pulled the EFI fuse and still have the code. Can anyone/anyone please help me out with this????? It would be nice to get this figured out.

Thanks!

thoff

iTrader: (1)

I think I have narrowed down the problem....

I changed ecu's and didn't get the light. I too only have 2 O2 sensors and don't have the 'secondary sensor' like some cars. I do have a plug inside the car for one but there was never one hooked up from the factory. I too got code 27 (secondary O2) and changing the O2 sensors didn't help. I changed ECU's and it seems to be okay now. I want to give thanks to slappy96 for hooking me up with a computer.

Thanks,

RyanV

iTrader: (9)

A friend of mine has the same issue.

Code 27 = Sub-oxygen sensor signal or heater circuit fault

Heater circuit...I'm thinking maybe the ecu coolant sensor is going bad or on the fritz.

Anyone else have any input?

thoff

iTrader: (1)

did your friend ever figure out the problem? was it the heater sensor?

I am having the problem with another car... when I take the ECU apart, you can see where it is burned on the lower circuit board right up next to where the connectors plug in. Really strange and I have seen this with several ECU's

Please chime in if anyone is familiar with this problem.

Thanks!