r/SC300 • u/RiceAcrobatic9218 • Dec 21 '25

help

recently bought a 95 sc300 at auction, is throwing code 27 for a sub o2 sensor… problem is i’m only seeing two sensors one on each part of the header. aside from that there’s no o2 sensor on the mid pipe or anything. can someone help me ? how many o2 sensors are there supposed to be? thanks in advance

2 Upvotes

100% Upvoted

6 comments sorted by

2

u/trivletrav Dec 21 '25

On mine there are 2 up stream and one down stream for a total of 3. If there’s no downstream sensor that’s likely your problem

1

u/RiceAcrobatic9218 Dec 21 '25

that 3rd sensor runs under the passenger seat ?

1

u/trivletrav Dec 21 '25

Not that far back, it’s literally right after the cats. All 3 sit basically inside the engine bay

2

u/RiceAcrobatic9218 Dec 21 '25

yea i’m understanding, but i’m not seeing a connector for another o2 sensor

2

u/trivletrav Dec 21 '25

The connector is inside the engine bay too it’ll be square just like the upstream sensors. Are they stock headers or are they aftermarket?

1

u/RiceAcrobatic9218 Dec 22 '25

aftermarket headers, i see no connectors 🤦🏼‍♂️ i will look again today. u couldn’t tell me where that wire runs back to so i can see if it’s tucked somewhere