ECU ODBII Diagnostics

[ricecube77]

Ignore me, I'm gay and i dont read other posts.

..... im really not gay, but ignore me.

(i got a 3/3 code....... O2 sensor. )

Anyone know how to check if O2 sensor is wrong? Or if the WIRING harness and ground for the O2 sensor is wrong? Read on Se-r lists, but not too clear about instructions on checking the wiring (grounding) or cheecking voltage for O2.


-Phil

[eeyore]

Two methods of checking:

1. Use a specialist lambda sensor diagnostic tool (expensive).
2. Use the ECU to do diagnostics on it (see Haynes manual, or sr20 sites will probably list).

These sensors are delicate, funny, little things. They don't just break, rather they gradually wear out over time. No easy diagnostic possible...

From what I've heard, the sensors gradually start to deteriorate from about 60,000miles onwards. 100,000miles is probably replacement time. Saying that, I'm on 80k and I've no reason to suspect anything.

Pulled mine out a couple of weeks ago and gave it a clean (carb cleaner). Fuel economy went up and the engine is running very nicely indeed.

[boingo82]

Hello there - I too have a 1994 G, and nearly 100k miles (99,090). About a month and a half ago, my check engine light came on and the car started to be sluggish. Very sluggish. I took it to the local Nissan dealer (this is before I obtained an FSM) and they diagnosed it as my front O2 sensor. They offered to replace it for $300. No way! I bought a bosch o2 sensor at Napa (bosch because they were the only brand offering different parts for front and rear sensors) and my dad and I installed it ourselves in 5 minutes needing only a wrench. If it is your front o2 sensor, I strongly recommend repairing it yourself. Any questions, just ask.

Emily

[ricecube77]

I have 3 O2 sensors currently. One old one of 82k mi. Another brand new. Another relatively new i bought from JGY. Connected each one here and there.... no help on my car.

Problem i found out later: DEAD ECU. Fried. Probably from a bad ground on the O2 sensor. Now with my new ECU im getting check engine light on..... signaling with 3 long 3 short lights (Front Heated Oxygen Sensor Equipment). O2 sensors... all 3, do not work. JGY sent me a used (relatively new) one from a perfectly working motor. My newly purchased Bosch 13039 doens't work either.

Suspecting a bad ground now on O2 sensor, which first fried my ECU.

I'll get more info once i ground the O2 and MAF (just to be safe later... and take care of the notorious MAF ground problem).

-Phil


(Basically i tried to changing O2 sensor thing.... i never did get a check engine light before i changed ECU's tho..... probably because my ECU fried.)

[boingo82]

Well, sorry to hear that. I have seen a lot of ECUs on eBay, though the one on there right now is 1991-1993 only. You might want to check local junkyards, and ask KBSlacker as he seems to have connections to several junked G's.

[eeyore]

Just for the record, the o2 sensor on my P11 (uk) is made by Bosch and has the bosch part number stamped alongside the nissan part number.

In other words, don't bother going to the main dealer - just unscrew the sensor and get the original bosch part number from it, then go down your local motor factors and pay 1/3 of the price.

Let me have a scout about - I'll try to find out exactly what wires go to the o2 sensor and give you some kind of diagnostic for them.