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Friday, February 01, 2019

Oxygen Sensors : R32 vs R33 O2 sensors

KH2 Nissan Skyline GT-R for sale in the USA.  Right hand drive Japanese classic car
Always finding out new things, often correcting issues or problems that we see. In this case it was an odd reading from an oxygen sensor.  This car originally had a Power FC, so it may have just been ignoring the factory oxygen sensors.

I changed ECU's on the car, and while checking out the readings, one 02 sensor was reading normally. The 2nd sensor was reading maximum, or 2.55 volts.  Unplugging the sensor, I saw 0 volts. So first thoughts are of course, the sensor is bad.  However I also thought it could be the wiring.  Since this car didn't have stock R32 sensors, it was always a chance.  After looking it the wiring diagram, then pinning out what I saw, I thought that two pins were swapped.

RHS 02 sensor showing 2.55 volts. LHS 02 sensor showing 0.54 volts
Factory sensors are what we normally call a narrow band 02 sensor. So if you are putting an R33 or R34 engine/turbos/outlet tubes in your R32 GT-R, and want the factory 02 sensors to "work", then you have a few options

  1. Run factory R32 GT-R outlet pipes and factory 02 sensors
  2. Run factory R32 GT-R 02 sensors with an adapter to fit the 12 mm sensors in the 18mm holes
  3. With R33/R34 sensors, swap two pins on the square 4 wire connector on the 02 sensor or chassis wiring. This will at least get the signal and power wires to the right spots to/from the ECU. 
Pin #1 and #2 swapped on the harness side of this R32 to match the R33 sensor wiring. 
The factory R32 GT-R oxygen sensors are titania sensors, and use a resistance value to give exhaust feedback to the ECU.  The factory R33 GT-R oxygen sensors are ziconium, and work on a voltage to give feedback to the ECU. Read more oxygen sensor information here.

They are also different sizes. The R32 GT-R sensor have a 12 mm thread, and use a 17 mm wrench to remove.  The R33 GT-R sensor have a 18mm thread, and use a 22mm wrench.

R33/R34 oxygen sensor wiring with pin out. The flat plug wiring is the same, the square plug wiring is not

Notice the color of the middle pin. Gold/brass color. This is the signal wire.  The same on R32/R33/R34

Notice the color on the upper right pin, which is pin #1. It needs to be moved to spot #2(lower right) for the reading to be correct. Then #2 pin to the upper right. 


Two pins swapped, both 02 sensors reading normally 

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