So I have had code 1001, an 0901 for a while now...
I replaced both o2 sensors and the codes didn't go away!
I just bought a brand new KS, because I read that that was a possible cause (I'm not getting a KS code, though).
I checked the fuse in the cabin, and it was good.
Any ideas as to why the codes aren't clearing?

I'm getting around 21 MPG still, and that's with regular city driving, highway, and a fare share of "spirited" driving........

Thanks in advance.

Mike

 

Hate to ask, but you did reset the ECU right?

 

Yeah, numerous times...

 

I figured you had as I've seen quite a few of your posts, But I try not to assume anything about anybody. Looking in my Nissan service manual there's about three pages of troubleshooting problems with the O2 sensors. Checking continunity between the ECM and the harness, testing voltage at specific pins, etc. One of the things is says to check is the two ground wires on the front of the intake. I can give you some specifics of voltage specs at harness connectors if you don't have a manual.

 

Those two harness grounds have nothing to do with it. The o2 sensors are grounded to the heads by way of the downpipe and exhaust manifold.

 

Just reading out of the Nissan Manual Page EC-144, If Check Input Signal Circuit is OK, then Loosen and Retighten Engine Ground Screws. (It has a drawing of the two screws labeled F18 & F19.

 

Yeah like another poster said reset the ECU and if that doesn't help then you need to check your knock sensor.

 

BUMP
If my car doesnt pass inspection by FRIDAY I'm going to get a $250.00 fine and my license will be REVOKED.
I'm screwed if I don't get this car to F'ing pass.

Mike

PS: I replaced the KS ( I HATE replacing Knock Sensors), cleared the ECU, and codes 0901 and 1001 came back............................

 

im having a similar problem( maybe similar). got a bad egr valve code. replaced the valve, and still cant pass inspection(check engine light cam back on). maybe the egr may the problem with yours. its an expernsive sensor though. found it for 120.00 at autopartsplace.com, which was 230 at the local parts store. The one i got from autopartsplace.com was an oem part too. My check engine light is still on. Any suggestions to which o2 sensor to start with? Any suggestions would be greatly appreciated. Im in the same boat as blackmaxx, im 5 months out of inspection.

 

Bump it up for some info.....
I have to have this figured out by friday or else I am SCREWED.....................................

 

if you have to get it done right away, i suggest you take it to a reputable mechanic. check 02 grounds.

 

LOL!! NOW THAT SUCKS!!!!!!! If worse comes to worse and your car fails emissions again, cant you simply tell them that you no longer drive the vehicle?

 

No.
It can't fail again.
It's 6 months past due on may 1st.... 6 months past due equals license revoketion and $250.00 fine.

 

What o2 grounds? See post number 5. The o2 sensors don't even have any ground wires.

 

Believe or not, the FSM has some errors and/or overlooked items. Coming from someone that has worked on maximas quite a bit in my short life, i can guarantee you that the harness grounds have nothing to do with the o2 sensors. The o2 sensors don't even have a ground wire. They have 2 heater wires, and one signal wire. The o2's are grounded to the heads by way of the y-pipe and exhaust manifold.

 

You're a smart man....
WTF is my problem??? hahahah

 

Did you recheck your work?

Make sure everything is plugged in properly, no bent pins? etc?

I'd re-do all the work, and see if this happens again.

 

Twice and three times and four times......
If it doesn't pass tomorrow (i'm going to try and clear the ECU and pray that it doesn't pop back up before they hook it up.
I can get two o2 simulators by saturday... but if i'm going to spend the money i'm just to just get two brand new OEM NISSAN sensors....
we'll see what happens tomorrow....

 

Don't believe it...Not for a second. The FSM may have typos, but there is no way that the engineers, (almost certainly electrical engineers), that authored the Engine Control section have no clue what they are talking about when they suggest that you check the harness ground. I've worked on cars for over thirty years and have a mechanical engineering degree, and I would not make the assumption that I know more than the engineers that designed and built the car.

 

Please explain to me, then, why the o2 sensors don't have a ground wire...

 

They are probably grounded via body to the car.

 

Well yes. They're grounded to the chassis, but not through a ground wire. This was my point originally. No ground wire = no harness ground on the lower intake manifold. The ground path is downpipe, exhaust manifold, heads, chassis.

 

Would you concede that the sensors themselves are but a single component of a larger system – the O2 sensor circuit, that is comprised of, (at the least), the sensor, the harness, and some of the internals of the ECM? The FSM has individual wiring diagrams for each of the engine control sensors, including the two upstream O2 sensors. The two harness grounds, (F18 & F19), are depicted in nearly all engine control sensors diagrams – the grounds connect to most sensors via “shield line wires.” Shield line wires apparently are a ground wire wound around one of the other sensor wires. I’m not sure why shield line wires are necessary, though their presence indicates that they are, (in my mind anyway). The shield line ground wire for the front bank sensor is visible on my car at the harness connector by the radiator as a wire wrapped around the white wire though it is covered with some type of electrical tape. This is clearly depicted in the FSM wiring diagram. I also ran into shield line ground wire at the knock sensor harness though I didn’t know what it was at the time. The KS is connected by a two-wire harness. One is a signal wire to the ECM; the other is a shield line ground that wraps around the sensor wire. I couldn’t figure out why the 2nd wire’s connector was missing at the final connector that plugs into the KS. I understand now – the second wire wraps around the first at the final 10” or so before it plugs into the KS. The KS also is indisputably grounded to the block via 12mm bolt. Reading the troubleshooting flowcharts for some of the other engine control sensors – nearly all list bad grounds at F18 & F19 as possible fault causes. Looking at wiring diagrams for the two 3-wire upstream O2 sensors. One wire is positive, two wires that carry the signal variance go to the ECM. Shield line wire covers the white wire to the ECM. The diagram for the 4-wire downstream sensor shows again one positive, two to the ECM, one to ground, shield wire again covers the white wire to the ECM. In looking through all of these pages and diagrams of the FSM it’s beyond question to me that the two harness grounds are necessary for the correct function of nearly all of the engine control sensors. So yes, your right when you say that the upstream sensors have no ground wire, BUT another component of the O2 sensor circuit, the harness, does have a ground that apparently is necessary for correct function of the system. If you can still somehow dismiss that the two harness grounds are necessary – could you concede that cleaning them can do no harm?

 

Right ON, Maxima 880!
The idea of getting a reliable ground through an exhaust pipe, crushable gasket, flex section, manifold, rusty bolts, etc all subject to roasting heat and oxidised to ****, is plain ridiculous.

 

I will concede that i didn't realize there was a shield line wire system in place to ground the o2 sensors. However, if those grounds were bad, a number of other components would be inop, such as the fuel pump, injectors, coils, etc.

 

Good Lord your stubborn.........Say UNCLE damn you.................

 

So 1000's Of Ppl Have The Same Problem, O2 Cel Keep Comming Up On My Baby 2, And No One Can Give A Streight Unswer.just Some Maybe This Maybe That, I Chenged Evrythinl All 3 Egr Sencors, But O2 Is Keep Commong Up And Ks.
I Know Me Screaming About It Not Gonna Do Any Good.
No One Knows Anything Any Way.
I Spend Arround $800 On All Of That May Be This May Be That, Becouse All The Shops I Went To Gave Me The Same **** May Be Thgis May Be That, ,and Any Time I Was Spending $$$ I Was Hoping It's Gonna Work This Time,but Still Dosen't. What About Nissan Dealer Do They Know What The Fack Is The Problem?

 

LOL check you out shutting a man up talking all that smart ****, LOL you came outta left field wit dat, but well spoken.

 

I know code 0901 is ks, but i can't even find code 1001.. 0901 is heater fault, i had that one

 

0901 is definitely NOT the KS.............................

 

did you get it fixed Blackmaxx96?

 

Blackmaxx96 and s600ergy, if you haven’t done so yet and your still looking to solve the problem you’ll probably need a multimeter and a manual. If you don’t have access to a manual, I’ll be happy to type some step by step instructions from the flowsheet of the FSM. I don’t think there’s a quick easy fix here as it seems your codes are coming from something other than the sensor itself. It will now require tedious step by step tracing of the harness circuits to find the problem. As for nismology, I have nothing but respect, he’s obviously intelligent and knowledgeable of mechanics. He makes relevant and concise points, and in all likelihood he’s probably right, I doubt that it’s the ground origin at the intake manifold because as he stated other systems would likely be affected. But it could easily be a problem with the ground circuit further down the line and when checking a circuit you need to start at an origin.

 

Thank you guys, this is off topic but lately I've seen a lot of bashing and "flaming" on people. You guys disagreed with someones advice, yet you didn't take it to a juvenile level. Thank you for restoring my confidence in this site although I know this is one step, its definitely in the right direction .

 

Like i told u all my cel came on again, i went to the shop this morning and i was so sure the code will be for o2. and i was surpriseD , it was ks and 1447 wich is EVAP. they cleand the cel, and told me to drive for a 20 min,but not On the hwy. i came back, no cel. so im due for the enspection soon, so they gave me pretest to see if car can pass the enspection AT NO CHARGE.
so 1447 is gone, but they told me if i were due for the enspection today she woudn't pass. becouse THE SNAP ON computer THAT THEY HAVE said: MONITORING SYSTEMS FOR EGR NOT READY, CAT NOT READY,O2 NOT READY.
WHAT THE FOCK IS THAT ALL ABOUT?

 

Sorry i got mixed up code 0901 is the oxygen sensor .. Upstream oxygen sensor heater fault (right bank) to be exact.. I had this exact same code

I put in ks instead of o2 sensor my bad...

Code 0304 is the ks.. I have that one also

 

a long shot...but did u check the 02 sensor fuse

 

The car started sputtering last night, and would die at idle sometimes... I check the codes again and 0303 was there too.
I replaced both o2 sensors with Bosch OE sensors and the 0303 code went away but 0901 and 1001 is still there.........
Bagh