What's up guy? I have a CEL and the code is high voltage reading from the secondary o2 sensor. It is a new o2 sensor, so I am leaning towards an open in the wiring. The voltage is reading 1.275 volts, I haven't tried jumping the o2 sensor to test the sensor that way yet.

Does anyone have any suggestions on an easy way or tips on finding the open.

I must add that this is the 4th o2 sensor that this has happened to, and I do know that it could be a bad ecu as well.

Any suggestions on not having this secondary o2 sensor throwing this code?

Kyle

 

How's your catalytic converter? and the first o2 sensor.

I had the p0420 code on my 99 Civic DX.
I bought 2 new primary & secondary o2 sensors, assuming they'd do the trick but didn't. Then went to gut my cat (welded into the manifold), didn't help. Then did this trick and have been having better mileage since and no CEL.
http://forums.clubrsx.com/showthread.php?t=296791

 

Have you made sure your car isnt running rich or lean? Also your Cat could be failing...

 

Do you have any exhaust leaks?

 

i would also inspect the wiring on the the chassis side of the harness running to the o2

 

Post car information and the CEL code.

 

98 Civic EX
d16y8
manual
p0138 is the code ..

i was going to jump the o2 sensor and then the ecu to figure out where the short is, but i was looking to wiring the o2 sensor directly to the ecu.

I was looking into the schematics, however I can only find 3 of the 4 wires that go into the ecu.

Connector A, terminal 5 BLK/WHT - which drives the heater
Connector D, terminal 13 GRN/BLK - ground
Connector D, terminam 14 WHT/RED - Signal

 

For P0138, you only need to concern yourself with the two wires at D13 and D14. Start there.

The code can also be caused by a bad ECU, if those two wires are fine.

 

are those two pins 1 and 2 in the plug for the o2 sensor?

 

Yes

1 = Red/Yel, D13

2 = Wht/Red, D14

 

and i know the part numbers from denso are different, but is the primary and secondary pretty much the same thing?

 

so i can jump the o2 sensor and check the voltage and if it still stays in high voltage, it's the ecu or the sensor?

 

i am having the p0138 code thrown. I looked into o2 simulators, but that wouldnt solve my problem. It's a wiring issue I believe.

The car is running lean because the o2 sensor is flat lining at 1.275 volts. Which means High Voltage = Running Lean

Since it is wiring that is at fault, an exhaust leak wouldn't do it.

I was thinking about this, but damn that would be a nice investigation haha. I was thinking about wiring terminal 1 and 2 of the o2 sensor plug directly to terminals d13 and d14 of the ecu.

 

so i did the scanner while pins 1 and 2 in the o2 sensor plug were jumped, voltage read 0.000 .. so it's just the o2 sensor that's bad .. I bought new hardware and gaskets today for the catalytic converter

 

anyone have any input?

 

i purchased a new o2 sensor, cat gaskets and new hardware kit (bolt and spring) ... so once i get a chance to install it all, i will update the thread