# Trouble code 75 and 39 -- Trans? Emissions? Fuel pump?



## emjay8 (Feb 29, 2012)

1999 Sentra GXE

I did the "screw turn trick" to get trouble codes 75 and 39, but there is a bunch of conflicting information online for what these mean. The 75 could be a trans issue, emissions, fuel pressure or even airbag.

Awhile back I bought a little Vgate bluetooth code reader off eBay for like $10, but it doesn't seem to work. The various mobile apps are able to connect to it, but it apparently doesn't work with the car unless I'm doing something wrong.

First it was just 75. 75 might mean 0750 from what I read, which is shift solenoid A. But the light is supposed to flash 10 times for "0" so I don't know why it wouldn't just say "0750" right out of the car. I added some trans oil since it was low and the check engine light turned off (perhaps a coincidence). But now about 100 miles later 75 is back along with 39 this time.

Does anyone have a definitive source as to what 75 and 39 mean?


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## smj999smj (Jan 1, 2006)

Those codes don't mean anything on a 99 model Sentra. I don't think you pulled the codes correctly. Personally, I would just drive to the local auto parts store and have them check the codes with a generic OBD II code reader; it'll be a whole lot easier and more accurate, IMO. Here is a site that has info on pulling codes on your model:

200SX ? 240SX ? Altima ? Frontier ? Pick-up ? Sentra ? Xterra (1996 ? 2004) ? OBD Trouble Codes


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## emjay8 (Feb 29, 2012)

I am 100% certain I read the flashing light correctly. I write the numbers down on a piece of paper. Big number for slow. Small for fast. That paper reads 53975397539753. 7 and 3 being the slow flashes. That leaves 75 and 39.

The car has taken a turn for the worse now. I started it to move it up the driveway some and it sputtered along the way. Now today it won't start. Last weekend when I turned the ignition (but not the engine) I heard a grinding noise coming from the rear that lasted only a few seconds. As far as I know, the only thing electronic and mechanical back there is the fuel pump. That happened on three occasions in a row that day, but then went away. I must have started the car 15 times after that going to a bunch of neighborhood garage sales that same day and the grinding sound never returned.

I don't have a fuel pressure gauge, but it appears to not be getting gas. When I turn the ignition I hear all of the usual sounds. Nothing absent. Nothing unusual. I suppose I'll check the fuel filter, backflush the line using gas and a squeeze bottle and then bang the fuel pump around a little to see if there is a piece of rust in it.


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## emjay8 (Feb 29, 2012)

Looks like I indeed wasn't reading the code correctly. 75 = 705 and 39 = 309 since short flashes are hundreds. Both EVAP. I'm guessing this is environmental protection stuff and that it has nothing to do with the car not starting.

Hooked a line up to the fuel pump line out and led it to a bucket. Turned ignition and it was pumping fuel. No idea about the pressure or what the optimal flow is supposed to look like though. It wasn't shooting out. Just kind of a calm flow. I'm still skeptical due to that noise I heard before. I'll get a fuel pressure gauge soon.


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## smj999smj (Jan 1, 2006)

Evaporative emission system stores fuel tank vapors in a canister filled with charcoal until a time when they can be drawn into the intake manifold and burned via the engine's normal combustion process. It normally doesn't create a starting issue. Finding out what the fuel pressure is would be a good idea.


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## jdg (Aug 27, 2009)

emjay8 said:


> The car has taken a turn for the worse now. I started it to move it up the driveway some and it sputtered along the way. Now today it won't start. Last weekend when I turned the ignition (but not the engine) I heard a grinding noise coming from the rear that lasted only a few seconds. As far as I know, the only thing electronic and mechanical back there is the fuel pump. That happened on three occasions in a row that day, but then went away. *I must have started the car 15 times after that going to a bunch of neighborhood garage sales that same day* and the grinding sound never returned.


I think you've just stumbled upon the worst thing about the B14 GA16DE...short drives.
It sounds completely stupid and counter-intuitive, but believe us all that know what's what, when we say what we say.

Don't ever drive this engine for a quick/short trip. It'll foul out the plugs almost every time and about the only cure will be new plugs.
I don't know why. I have my theories and one half-baked theory that seems to work but I need to do more testing.
For some oddball reason, whenever you fire up the engine for a short drive, the plugs foul themselves out. The ECM just commands a buttload of fuel and wrecks the plugs. Don't know why, don't care why.

1st thing, pull the fuel pump fuse, pull the plugs, crank it over for awhile, get all the fuel pressure out of the system, let the cylinders blow themselves completely dry, blow the plugs dry, or better yet, just replace the plugs with new NGK (and ONLY NGK) plugs.

2nd, put everything back together and see what happens.

By short drives, I mean the kind where you fire it up, head down the driveway to get the mail and come back, or maybe go around the block once, stuff like that.
I think the cure is to run it long enough to get the engine to go into closed loop operation, which can take up to a few minutes. That's part of my theory, but don't bet money on it just yet. I haven't done enough testing yet to confirm anything.

As far as the fuel pump noise...sure, could be the fuel pump. The pump itself could be sitting on old bushing and vibrating itself all around, or maybe that day you just had a weird combination of lower than normal fuel levels, an old fuel pump that was partially exposed on an emptyish tank, worn bushings, etc.etc.etc. Once you get the fuel pressure gauge, you'll know for sure. Otherwise, if it accelerates halfway decent, and you don't get any check engine light, I'd be willing to bet your fuel pressure is good. And keep in mind, this is a GA16DE, a 1.6L engine designed for decent fuel mileage. It's not a power house. They last forever if treated right. It's not going to win any 1/4 mile races


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## emjay8 (Feb 29, 2012)

Haven't worked on it much the past couple days.

Back when I got the car in 2012 I had a pre-purchase check done at a nearby garage. He said the spark plugs were the originals from 1999, but the plug wires had been changed. I haven't changed the plugs since then either, so they've got 16+ years and about 46,000 miles on them (yes, it's a very low mileage 1999).

Here are some photos I took:

The carbon buildup is looking pretty bad. I saw somewhere on NGK's website that you can sandblast this off, but I don't have a blaster. Normally I'd try a wire brush on my grinding wheel, but it seems as though I should just replace these given their age.









This burning didn't look right. A little research says it's compression leakage of the plug and it may damage the ignition coil.










About the many short trips issue, NGK's site says a higher heat plug can help with the carbon buildup (but at the risk of pre-detonation). Nissan's official repair manual lists a couple high heat plugs. I'll probably get the standard plugs and just keep an eye on them. I have no idea what you see in that photo is my own driving habits versus the previous owner or just age.



No check engine light. Decided to check for a code anyway. Gave me code 402 using the screw turn method.

402
Fuel temperature sensor- circuit malfunction
Wiring, fuel temperature sensor, ECM

Seems a little weird that it comes up only after I took the gas access hatch off and pulled things out a bit. Perhaps I knocked something loose. I still haven't taken the pump out for visual inspection. I watched a video for a B15 Sentra I think it was and it threw me off when the B14 pump apparently isn't attached to that first piece that pulls out.


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## jdg (Aug 27, 2009)

Yep, those plugs are done. Tip is rounded off, side electrode is worn down. Time for new ones.

The burning - I wouldn't worry about it. Crud gets down in the plug tubes over time somehow, kinda settles on the plug, burns on, stays on. Now if it was a thick layer of goo, then ya, maybe I'd worry about it, if it showed up within a couple hundred miles and within a couple days.

I wouldn't get the 'next higher heat plugs' unless you know you've got an issue or a driving situation that warrants it. Stick with stock.

Code 402? Not buying it, since the B14 doesn't have a fuel temp sensor...
Sure it wasn't a 420 or 42?
Borrow an OBD scanner (or buy bluetooth one on Amazon for ~$10), use your phone (+bluetooth) to grab codes, performance data, etc. Read the codes using that vs. the screw turn method.


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## emjay8 (Feb 29, 2012)

jdg said:


> Code 402? Not buying it, since the B14 doesn't have a fuel temp sensor...
> Sure it wasn't a 420 or 42?


Four long flashes and then two short. TroubleCodes.net says:

Long flashes indicate the ‘hundreds’ of the trouble code
Short flashes indicate the ‘units’ of the trouble code



jdg said:


> Borrow an OBD scanner (or buy bluetooth one on Amazon for ~$10), use your phone (+bluetooth) to grab codes, performance data, etc. Read the codes using that vs. the screw turn method.


I already bought one of those off eBay. Vgate was the brand. I downloaded a dozen different apps and also tried the software that came on the CD. They connected with the reader, but none could get data from the car.

Perhaps I didn't get the right reader. Does anyone know of a specific model of these cheap bluetooth readers that will work on a 99?


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## jdg (Aug 27, 2009)

Obd is obd is obd.
Ive got 3 different brands/types, but they're all the same $10 crap. Only 2 works. I let the smoke out of the 3rd one. I use torque lite on my phone. Works just fine. Got a link to your particular model? Key has to be on to pull codes.


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## smj999smj (Jan 1, 2006)

I keep a $65 generic OBD II code reader that I purchased from Walmart about five years ago in my glove box. Works great and comes in handy. I'm sure you can get it for cheaper, these days. It doesn't do datastreaming or any more than show what ECM codes triggered and how many times and it allows the ability to erase them. For diagnosing problems, I would recommend something better, but just for something to retrieve and erase codes, it's been great.


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## emjay8 (Feb 29, 2012)

*UPDATE:*

I got a fuel pressure gauge off of eBay. Harbor Freight one. The aluminum "T" hookup was closed off about 50% on one side and needed to be deburred. Luckily I had a metal file that fit in.

Pressure gauge after fuel filter. Ignition on (but not started). About 45 PSI. Pump runs about five seconds. Stops. Pressure quickly drops to about 12 PSI.
VIDEO:
https://youtu.be/uPKiGxADCzM

Pressure gauge after fuel sending unit outflow under the rear seat. Ignition on (but not started). About 62 PSI. Pump runs about five seconds. Stops. Pressure goes down slower here. Takes one minute to reach about 35 PSI. Settled at about 15 PSI before I unhooked it.
VIDEO:
https://youtu.be/3j6mwplQxaA

Pressure gauge after fuel filter. Ignition on primes system to about 45 PSI. I attempt to start the car with the system primed. PSI bounces around low to mid 40s. Will not turn over. Left the gauge on and it read 0 PSI the next morning.
VIDEO:
https://youtu.be/rIgMkD9TpRE


One other potentially related thing is the $50 WalMart "Value Power" battery I put in the car a few months ago. From day one it took two or three extra cranks to start the car compared to my 9+ year old NAPA battery that I kept adding baking soda to. The day my car sputtered and died as I was moving it up the driveway, I had been running the radio for a pretty long time while cleaning the car (Scotch Guard vinyl and leather cleaner made the dash, steering wheel, door pannels, etc. look like new by the way). Could a battery problem have started the car but then caused it to sputter like that once I was moving? I put a 12v 2A charger on the car for a few hours last night. Then it sat for 12 hours and now it's testing at 12.53 volts. This isn't the first time I've noticed what seems to be low voltage on this battery.


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## emjay8 (Feb 29, 2012)

This is the code reader that I have that doesn't report anything to the various apps (including Torque Lite):










I imagine there are probably a number of Chinese companies producing something that looks exactly like that. Perhaps some work and others don't.


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## jdg (Aug 27, 2009)

emjay8 said:


> Pressure gauge after fuel filter. Ignition on (but not started). About 45 PSI. Pump runs about five seconds. Stops. Pressure quickly drops to about 12 PSI.


Pressure should hold for days, weeks, months, years, decades!
Or at least overnight.
Rotten check valve in the pump itself.



> The day my car sputtered and died as I was moving it up the driveway, I had been running the radio for a pretty long time while cleaning the car (Scotch Guard vinyl and leather cleaner made the dash, steering wheel, door pannels, etc. look like new by the way). Could a battery problem have started the car but then caused it to sputter like that once I was moving? I put a 12v 2A charger on the car for a few hours last night. Then it sat for 12 hours and now it's testing at 12.53 volts. This isn't the first time I've noticed what seems to be low voltage on this battery.


Did you do another "short drive" with the new plugs?
Or have you even replaced those rotten plugs yet?
I've heard that same noise while cranking...that noise of only one or two cylinders firing due to fouled out spark plugs...
Change the plugs if you haven't already.
If you have changed the plugs, and this new sputtering happened afterwards, take them out, blow them completely dry, crank the engine over with the fuel pump fuse out to blow the cylinders dry, and try again.

BTW...that fuel pressure gauge looks like a fantastically cheap piece of Harbor Freight sheeot. Those readings you were getting when it read 62PSI I think are complete B.S. and that at that particular time, the gauge itself was reading 12PSI high but only because it bled down similar to the other video.
I wouldn't believe any numbers that gauge has on it and would only trust it to indicate whether or not there is some pressure or no pressure.


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## jdg (Aug 27, 2009)

emjay8 said:


> This is the code reader that I have that doesn't report anything to the various apps (including Torque Lite):
> ....<SNIP>....
> I imagine there are probably a number of Chinese companies producing something that looks exactly like that. Perhaps some work and others don't.


Yep, it's pretty much a crap shoot as to whether or not they work.
At least they're most of them are cheap enough to be almost throw-away items.


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## emjay8 (Feb 29, 2012)

I haven't gotten the new plugs yet. They look pretty bad, but doesn't seem like a primary problem at the moment.

I figured that pressure gauge was low quality, but I didn't want to pay $50... $75... $100+ for something I may not need again for years and years.

I'll pull the fuel pump out next.


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## jdg (Aug 27, 2009)

emjay8 said:


> I haven't gotten the new plugs yet. They look pretty bad, but doesn't seem like a primary problem at the moment.


Ok, here's how it works...

Before changing plugs, doesn't start.

After changing plugs, does start.



> I figured that pressure gauge was low quality, but I didn't want to pay $50... $75... $100+ for something I may not need again for years and years.


Agree, as long a guy understands the limitations of the equipment being used. In other words, the pressure numbers are useless but at least you know you have some pressure. Gauge may as well say something like NO at around zero and YES anywhere else.


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