'96 D21 w/ KA24 oxygen sensor code

Forum for the Xterra, Frontier and Hardbody, the smaller workhorses of the Nissan lineup!
SolowKaver
Posts: 18
Joined: Sat Mar 07, 2020 4:19 pm
Car: 97 Hardbody 4X4

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After a cylinder head warp repair, new timing chain, new clutch, and some minor repairs I got my hardbody engine etc. all back together, installed, connected and finally started it up. It ran rough and had a very low idle at first with check engine light on. Mt scanner reported a crank position sensor code and an oxygen sensor code. I cleared them and started it back up and it ran better but not great with no check engine light. I shut it down and did the oxygen sensor test on my scan tool and it came out good on all banks etc. When I started it up after that is ran perfectly. I went on a short cruise and it ran as good as it ever did with good power and smoothness. At least I confirmed the engine appears healthy. I shut it down for the evening and next day started it up again but this time it wouldn't idle at all and ran awful. Check engine light was on again and the same codes reappeared. This time it refuses to clear the oxygen sensor code (bank 1) even after multiple attempts. I grabbed a Bosch "direct fit" replacement sensor from local parts store but it only has a single wire compared to the three wires on the original oxygen sensor. Since the sensor is nearly impossible to get out without some special socket I don't know what to do next. For now I unhooked the battery overnight to see if that might clear the code.

It has 220K miles and was running fine when the plastic radiator hose connection failed that overheated it and warped the head in February.

Is the single wire replacement oxygen sensor usable and if so which wire do you attach it to on the harness?

Could it be corrosion on the computer contacts making it act strange (it's been 4-5 months since I drove it last)?


SolowKaver
Posts: 18
Joined: Sat Mar 07, 2020 4:19 pm
Car: 97 Hardbody 4X4

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OK after more searching I found out I got the wrong upstream sensor with a single lead instead of the Bosch 13416 three lead unit. I also found out there is a four conductor lead downstream O2 sensor after the cat in the exhaust. Since I spewed some coolant through the exhaust system when the head gasket blew I figure the downstream sensor is probably more affected - especially since some moisture was still in the exhaust blowing out steam when I fired it up after the repairs.

Does anyone have any opinions or suggestions other than start replacing stuff and see what happens? Thanks!

SolowKaver
Posts: 18
Joined: Sat Mar 07, 2020 4:19 pm
Car: 97 Hardbody 4X4

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Some "duck duck go" searching produced this informative website - easyautodiagnostics/nissan/2.4L/ which has plenty of useful info on what I am dealing with and maybe some simple tests to solve it. We'll see....

BTW I am not associated with that site but it seems to be helpful and may help some of you too.

whomadewho
Posts: 523
Joined: Mon Aug 02, 2010 9:32 pm
Car: 1997 Nissan pickup

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Might try following the wiring harness on the down stream 02 sensor. The cable is long and goes to a connector located on the frame rail. Possibly the connection plug is corroded? IF all possible without destroying the sensor you might? try removing the sensor and clean the end? Check to see if you have power going to the sensor? Possibly could have a restriction going on in the catalytic converter or muffler? Check for good flow out of the tail pipe.

SolowKaver
Posts: 18
Joined: Sat Mar 07, 2020 4:19 pm
Car: 97 Hardbody 4X4

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Thanks whomadewho! I actually have been checking the sensors and found both of them to have about 4 ohms resistance. The connectors look fine as well. I'm waiting on a special 7/8" O2 sensor socket from Jegs to be able to try to remove the sensor and either clean them or replace them but it's on back order. Yesterday I unplugged both O2 sensors and started the truck and it runs fine. Idles smooth and has good power. I drove it about 10 miles at up to highway speeds and it seemed to run as good as always. If I plug in either or both sensors it idles like crap and my scanner shows me the fuel injectors are being starved of fuel. If I rev it off idle it smooths out some but the fuel circuit eventually gets starved again reading -25% or more cycling between normal 0% fuel load (smooth idle) and some negative values (rough idle - tries to die). I ordered both O2 sensors and have them in hand so I figure I'll change them out when the tool arrives. Is there any harm in running with them disconnected (other than emissions control) ?

whomadewho
Posts: 523
Joined: Mon Aug 02, 2010 9:32 pm
Car: 1997 Nissan pickup

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Good luck hope that solves the problem If the problem still exists you might want to check voltage at the fuel pump pressure regulator and the injectors especially number 4.

SolowKaver
Posts: 18
Joined: Sat Mar 07, 2020 4:19 pm
Car: 97 Hardbody 4X4

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Thanks whomadewho. BTW the exhaust flow is fine so hopefully the cat is OK. I haven't checked voltages on the sensors yet either but the 15 amp fuse is good that powers that circuit. Would low voltage at the regulator throw a code? Only code I have is for O2 sensor bank 1.

SolowKaver
Posts: 18
Joined: Sat Mar 07, 2020 4:19 pm
Car: 97 Hardbody 4X4

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Got the special O2 sensor removal tool yesterday and removed the O2 sensor on the exhaust manifold, replaced it, plugged in both O2 sensors, and all is well! Runs great and NO codes! Thanks to all that gave me help and encouragement.

whomadewho
Posts: 523
Joined: Mon Aug 02, 2010 9:32 pm
Car: 1997 Nissan pickup

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Greatly appreciate the updates. Helps others experiencing the same situation.


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