I have a b16a1 motor with two o2 sensors. They are exactlly side by side, which is primary and which secondary???????

 

the oxygen sensor shouldnt be side by side like that. usually the sensor closer to the head cylinder is primary and the other is secondary. what year car is this i dont no much about these engine codes.

 

It's a '90 JDM b16a1 motor

 

i think by side by side he means off of the car. if so just plug them in and i it throws cel switch them around. if they are on the car....the primary should be on the exhaust manifold and the secondary should be on the catalytic converter

 

The primary O2 sensor is the sensor closest to the transmission. The secondary O2 sensor is the sensor closest to the driver's side. The secondary has a green plug of a different shape than that found on the stock engine; the primary sensor has the same style plug (so you can't mix them up that way).

As was suggested earlier, my car suffered part-throttle detonation under part acceleration in cylinders #3 and #4. The (temporary) solution to this problem is to simply unplug both of the O2 sensors from the wiring harness at the ECU end, thereby leaving the O2 sensors connected insid the bay (so you pass tech inspections, and can still use them for an O2 sensor gauge, like your Autometer). Don't bother unplugging them if you don't have the problem . And a quick note: Unplugging both the sensors will cause a CEL from time to time (mine comes on after roughly half an hour of driving, less time than that if I do lots of engine braking), but ignore this - the redline will not be affected, and the computer will not be running in backup mode.

Have fun . Hope that helped.

Here's a fuzzy picture: