Code 27, Sub O2 Sensor Signal

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Dec 25, 2016 | 08:45 PM

Deegee

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Lexus Test Driver

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From: TX

Code 27, Sub O2 Sensor Signal

I'm receiving a Code 27, Sub O2 Sensor Signal. Correct me if I'm wrong, but I believe this code isn't indicating that an actual O2 sensor in the car has gone bad. But instead, the O2 sensor signal needs to be replaced.

I'm not sure if it makes a difference but my car is a 92 SC400 with w58, headers, and y pipe exhaust, and no cats. Is there anything I can do to clear this code without cats? Various threads I've been reading state that this code doesn't necessarily interfere with the performance of the vehicle (gas mileage) nor does it mean to replace all your O2 sensors (4 i believe in the SC400). Any advice would be appreciated.

Thanks.

Dec 27, 2016 | 02:58 PM

Deegee

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Lexus Test Driver

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Bump. Read a few threads and still aren't sure where to locate the Sub 02 Signal. TRAC light isn't on either.

https://www.clublexus.com/forums/sc-...code-27-a.html

https://www.clublexus.com/forums/sc-...o2-sensor.html

This doesn't seem to be a common issue from what I'm gathering.

Feb 28, 2018 | 10:52 AM

Deegee

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From: TX

Bringing this thread back from the dead.

I'm confused as there are three different codes for O2 sensors on these cars.

27
Sub O2S Signal

28
Main O2S

29
Sub O2S

What is an sub o2 sensor signal (27)? This is what I'm having problems with.