1999 Q45 throwing codes 138 and 139

[poweroptions]

I have a 99 Q45 with 43,500 miles. I've always ran 93octane fuel. It threw a code P138. My mechanic replaced the right rear O2 sensor with NGK/NTK new sensor. At the same time he replaced all the spark plugs with OEM NGK $$$ plugs. Drove it home 30 miles and the service engine light was out. Now after sitting a week in my garage, I started it this morning and the engine light came on. I took it back to my mechanic and now it is showing codes P138 and P139. He doesn't know why and told me he didn't want to work on my car anymore. DOES ANYONE OUT THERE HAVE AN IDEA WHAT I'm DEALING WITH????? thanks

[Bwana]

The Q guys will be able to help ya more than Gen chat regulars.

Moved to Q45!

[bullittandy]

O2 sensors are a wear item so you would do well to replace the rest of them-kind of expensive but it will likely solve your current problem. There's a great post written by a real clever guy somewhere here on how to replace them.

Good luck!

[poweroptions]

OK so now I replaced all O2 sensors. Still service engine light is on. Code 138 and 139 again. I'm out more $$$$. Does anyone have any suggestions. It will have a moment of rough idle when I'm sitting still at a stop light once in a while. Any other time it runs like a rocket ship.

[maxnix]

Might want to read the stumble threads here.

Many think replacing O2 sensors cures it. Sometimes yes, sometimes no, sometimes it is not enough. You might well be in the 3rd category.

Didn't you post this in IOM also?

[bullittandy]

OK so now I replaced all O2 sensors. Still service engine light is on. Code 138 and 139 again. I'm out more $$$$. Does anyone have any suggestions. It will have a moment of rough idle when I'm sitting still at a stop light once in a while. Any other time it runs like a rocket ship.

I think you've got two problems at once. The codes 138 and 139 should be gone with the O2 sensors replaced-did you reset the Check engine light?

The rough idle is a well-known problem with no clear solution, check for the recent posts on it.

[blackran]

yo! if you light went and then came back on later...is the car running fine?if so i just had the same problem.. what you want to do for that is disconnect the battery for at least 24 hours..the sensors that that catch the codes has in it's own separate battery..you have to let the battery that runs the codes go dead so it won't keep telling you to service the engine..

good luck..

[Q45tech]

There are no backup batteries in ecu [other that a filter capacitor which exhausts in 10-15 seconds].

The codes are stored in memory which has a 20 year life just like a USB memory stick.

Clearing codes requires a correction of the problem and an OBD2 scanner reset. [clear code signal].

Amazing urban legends concerning how things work.

[Q45tech]

Technicans spend about 40 in class room hours studying simple OBD2 operation, then another 40 on advanced trouble shooting, the another 40 on sensors and testing of sensors.

Granted few technicans have achieved these levels of competence as these things are recent additions to the 2 year AASE/T program but OBD2 has been around for 12 years now.

The point is there are no simple solutions we can give here other than education at the level of technicans hopefully members will spend their 120 hours of class room instruction.

[Q45tech]

Important to equate a 9 year old abused by sitting car with the eqivalent mileage of 140,000 not the 40+k it reads on odometer.......many more components DIE from old age than high miles!

Things designed to last 7 years or 100k can easily fail after 9 years and 40k.

[poweroptions]

Another Q owner was in my store today and we were talking. He said I should take my Q to Nissan or Infiniti and have the ECM reset. I asked my mechanic if he could and George said no he only cleared the codes with his handheld OSB II when he replaced the O2 sensors, that he didn't have the setup(computer) the dealership would have. Is resetting the ECM the same as me disconnecting the battery for 24+ hours??

[blackran]

THANKS GURU TECH...BUT IT DID WORK FOR ME ARTER I HAD MY FRONT RIGHT SIDE OF MY CAR REPLACED...I'M FOR SURE 98'Q45 ARE NOT LIKE 90' Q'S

[maxnix]

THANKS GURU TECH...BUT IT DID WORK FOR ME ARTER I HAD MY FRONT RIGHT SIDE OF MY CAR REPLACED...I'M FOR SURE 98'Q45 ARE NOT LIKE 90' Q'S

Three points:

1.) YOU DON'T NEED TO SHOUT! We can read quite well, thank you.

2.) He knows about OBD II, I can assure you.

3.) You may well be confusing coincedence with cause and effect.

[maxnix]

Another Q owner was in my store today and we were talking. He said I should take my Q to Nissan or Infiniti and have the ECM reset.

Reset? Really? Might ask him if he has ever read the FSM.

[gammer_ghn]

Reset? Really? Might ask him if he has ever read the FSM.

Three points:

1.) YOU DON'T NEED TO SHOUT! We can read quite well, thank you.

2.) He knows about OBD II, I can assure you.

3.) You may well be confusing coincedence with cause and effect.

OOOOOOOOOOOOOOOHHHHHHHHHHHHHHHHHHHHHHHh Snap the war is on = ] i love this when its not involving me ahhh the good life now you guys can be nice and check out what i posted and put some answers on there thanks!!!

zerothread/289006

[poweroptions]

Well, I'm trying to get my 99Q to run perfect. It is showroom new, 43K miles stays in my gargage, never out in Texas sun or rain and sure as hell hasn't been ramrodded around. It's a damn shame when someone else is in the car and we are sitting at a redlight and the car shakes and stumbles and you think it's going to die. It's a damn nice car and shouldn't do that. My mechanic George has looked at most everything. He says it all looks brand new. The plugs he replaced still are in fantastic condition. All of the o2 sensors looked good(who knows). He told me to keep them for in the future. We disconnected the battery and left the car sit for a day and a half. I've now driven it a couple hundred miles and no lights on the dash yet. It did stumble when I pulled up to my mailbox yesterday. It has 99 octane racing fuel in it that I put in. That sure woke the ***** up.

[poweroptions]

Call me dumb, what's FSM ?????

[Q451990]

FSM = Factory Service Manual. The site http://www.phatg20.net seems to be working again now. You can download the manual and then google for the software you need to decompress the .rar file you downloaded into a .pdf

Good luck!

Heath

[maxnix]

Call me dumb, what's FSM ?????

http://www.nicoclub.com/FSM/Q45

[gammer_ghn]

Well i don’t know man but mine drinks Ca 91oc and i got a 99 too and just barely a month ago i hit 103000 ive had her since 67k if you are having these problems that early on either the car wasn’t broken in right or you got your self a lemon Q "that’s very rare” or the mileage has been turned back.... so what you see is not what you get at the moment i guess there has been a thread on this problem i think you should read it = ]

zerothread/273981

And welcome to nice and why don’t you put up pix and everything in theshow us your ride portion = ]

zerothread/276707

sorry you had to join us with a problem but a little reading and searching will get you there perfectly trust in the power of Nico the old schooleres here don’t like to see that you don’t search so play ball by the rule of Nico which I learned the hard way you will do lovely here!!! Trust me

[96Qowner]

Reset? Really? Might ask him if he has ever read the FSM.

Probably talking about that TSB regarding "reprogramming" the ECU to account for slow O2 sensor heating.

[maxnix]

Probably talking about that TSB regarding "reprogramming" the ECU to account for slow O2 sensor heating.

There was one, but it was triggered by fuel economy, I thought. Don't have TSB with me.

[StarPD]

I think you've got two problems at once. The codes 138 and 139 should be gone with the O2 sensors replaced-did you reset the Check engine light?

The rough idle is a well-known problem with no clear solution, check for the recent posts on it.

Just a wild guess, but MAF?

[poweroptions]

Pampered with a capital P. Broken in gently I bought it new. Never a singlre glitch in 8 years till now. Love the car as well as everyone else that sees it. I tried to download pictures but this website is not the easiest. I am new to this NICO sight and am trying to learn the ropes without being bitched at.

[poweroptions]

Sewell Infiniti just sent me a TSB regarding 1999-2001 Q45 MIL"on" Rear O2 Sensor DTC P0138,P0139,P0140,P0158,P0159,P0160. The technician explained there are problems with the DTC stored in the ECM. He might as well been speaking Polish to me. What does DTC stand for?

[maxnix]

What does DTC stand for?

Start at EC-115 and keep reading.

[poweroptions]

THANK U MAXNIX for the info you supplied. It's a helluva alot easier to work on my old Thunderbirds and Lincolns thou. This Infiniti is way over my head.

[maxnix]

I remember changing the water pump on the 1964 Bird involved opening the AC system to move the compressor out of the way. The VH45DE is particular but simple once you understand the FSM, TSB, and read all the valuable posts here.

I am afraid you need to have a Senior Infiniti Technician with an OBD II scan and diagnose your car though. Something has been missed in maintenance (time wounds all cars, especially rubber) or something like the CAS or MAF connector is bad.

[bullittandy]

Well, I'm trying to get my 99Q to run perfect. It is showroom new, 43K miles stays in my gargage, never out in Texas sun or rain and sure as hell hasn't been ramrodded around. It's a damn shame when someone else is in the car and we are sitting at a redlight and the car shakes and stumbles and you think it's going to die. It's a damn nice car and shouldn't do that. My mechanic George has looked at most everything. He says it all looks brand new. The plugs he replaced still are in fantastic condition. All of the o2 sensors looked good(who knows). He told me to keep them for in the future. We disconnected the battery and left the car sit for a day and a half. I've now driven it a couple hundred miles and no lights on the dash yet. It did stumble when I pulled up to my mailbox yesterday. It has 99 octane racing fuel in it that I put in. That sure woke the ***** up.

There's alot of talk about these cars stumbling. It's my guess after reading all of the previous posts about the stumble that it is an intermittent coil problem.

What's interesting is that one of the first solutions that I read about this was several years ago and the dealer wanted to replace ALL the coils. That's a little much but they (dealer and any other dealer) knows the problem, a bad coil.

If it were me, I'd buy ONE coil and starting at the first cylinder on the passenger bank, start swapping out the coils until the stumble disappears. If a dealer or ind shop can moniter individual cylinders then this would be much faster.

[poweroptions]

I wanted to say THANKS to everyone and their input. Infiniti reset the ECU and 500 miles later no stumble and no MIL "on". Tech said this is a usual problem with 99-01s and there was no charge. They luved my car and were blown away with the condition it is in. Wanted me to trade it in but I said no way. I'm due a new pickup next. patrick