What is that plug under the exhaust manifold? - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

FortuneKouki420 · 11-22-2011, 03:17 PM

My ECU is reading a rear o2 sensor circuit malfunction and I can't find the rear o2 sensor on my cat. My car is 95, ODB2 and I initially thought it was ODB1 so I changed the front o2 sensor but the engine light came back on. Can someone tell me what that plug is? I checked the FSM but without success.

(burrowed this picture)

I was at an autobody at first and the guy told me that plug is the rear o2 sensor.. I think he's bullshitting.. because the rear o2 should be right there but I can't find the slot after my cat! WTF. I can't find the rear o2 wire either. Thanks.

silver350z05rb · 11-22-2011, 09:33 PM

The last picture you posted,is the 2nd sensor,not sure why you are missing it

rcdad123 · 11-23-2011, 01:02 AM

OBD 1 only have 1 o2 sensor. obd 2 have 2. one on the manifold and one on or after the cat. the plug you were looking at is for air injection.

mikerbike · 11-25-2011, 11:47 AM

Your first two pics show an S13 exhaust manifold and downpipe. The last picture is an S14 downpipe/cat.

S13 only have one O2 sensor. So if those two first pics are your S14, you need to find another manifold/downpipe, or weld another O2 bung on.

11-22-2011, 03:17 PM	#1
FortuneKouki420 Join Date: Jan 2009 Location: Davis, CA Posts: 17 Trader Rating: (1) Feedback Score: 1 reviews	What is that plug under the exhaust manifold? My ECU is reading a rear o2 sensor circuit malfunction and I can't find the rear o2 sensor on my cat. My car is 95, ODB2 and I initially thought it was ODB1 so I changed the front o2 sensor but the engine light came back on. Can someone tell me what that plug is? I checked the FSM but without success. (burrowed this picture) I was at an autobody at first and the guy told me that plug is the rear o2 sensor.. I think he's bullshitting.. because the rear o2 should be right there but I can't find the slot after my cat! WTF. I can't find the rear o2 wire either. Thanks.

11-22-2011, 09:33 PM	#2
silver350z05rb Zilvia Junkie Join Date: Apr 2008 Location: California Age: 38 Posts: 432 Trader Rating: (9) Feedback Score: 9 reviews	The last picture you posted,is the 2nd sensor,not sure why you are missing it

11-23-2011, 01:02 AM	#3
rcdad123 Zilvia Addict Join Date: Jul 2011 Location: san diego Posts: 639 Trader Rating: (0) Feedback Score: 0 reviews	OBD 1 only have 1 o2 sensor. obd 2 have 2. one on the manifold and one on or after the cat. the plug you were looking at is for air injection.

11-25-2011, 11:47 AM	#4
mikerbike Zilvia Junkie Join Date: Apr 2007 Location: SLC, UT Age: 42 Posts: 461 Trader Rating: (0) Feedback Score: 0 reviews	Your first two pics show an S13 exhaust manifold and downpipe. The last picture is an S14 downpipe/cat. S13 only have one O2 sensor. So if those two first pics are your S14, you need to find another manifold/downpipe, or weld another O2 bung on.