Trouble Code p1464?

[CHAVEZ]

My 2000 xterra has a p1464 code stored on the comp. Supposedly this code should not exist for my vehicle and I guess i agree since I can't find hardly any info on it. I called the dealership and talked with a tech, he says that code does not exist but its sure there. I've had three different scan tools read it. I'm also unable to clear the code with any scanner, the only way to do it is to disconnect the batt overnight even then it will come back on after the first trip. Does anybody know anything about this?

[DamnHippie]

Everything I can find says that for a Nissan, P1464 is "Fuel Level Sensor Circuit (Ground Signal)". Since the second digit is a 1, that means it's a Nissan-specific code, and a variety of sites agreee that a nissan 1464 is fuel level sensor.

On my 99, my gas gauge and idiot light have been flakey lately (idiot light on when there's 3/4 tank, that sort of thing), but I don't have any codes about it. On mine, I think the problem is in the dash/gauges. But there is a recall affecting older frontiers, and I think xterras too, about corrosion in the electrical connectors at the fuel sender. I had that problem and had to have the sender replaced a few years ago. That problem especially affects vehicles where salt is used a lot on the roads in the winter. The plastic on the connector cracks, then salt gets in and corrodes the copper connections.

[CHAVEZ]

Ya I found that information too about the code but nissan's telling me that it shouldn't exist on the xterra model. My car is actually in the shop right now getting that saftey recall done. Maybe that will fix it?

[CHAVEZ]

Well gitting the recall done did not fix it. I'm stumped, I checked the circuit to ground and its fine. Any ideas?

[Allen Cox]

It does exist in the Xterra.

Getting the recall will help only if they have to replace the sending unit.

Is your fuel gauge reading erratic? Checking the ground circuit, from where to where? Did you check it through the sending unit, and through it's full range?

Probably needs a sending unit anyway. You can either hope that it get's replaced during the recall or just get a new one installed.

[CHAVEZ]

They did end up replacing the unit. No it's never really acted erratic for me. All I did when checking the ground circuit was check continuity between the ground side of the connector and ground on the chassis. Could it be anything else with the fuel delivery system? When I try to clear the codes with the scan tool it won't ever erase this code although it turns the light off. and when I turn on the car and run it for a few secconds the light will come back on. Then when I read the codes it says there are two codes stored on the comp but there both the same code p1464. It also says that it has freeze frame data for one of the codes and in that data the only thing that I can see that might be the problem is that: Fuel system 1---OL and Fuel system 2---OL. I assume that it means somthing is out of limmit? but what? Thanks for your help

[Allen Cox]

Did this happen after the sending unit was replaced?

Do you have a low fuel light that comes on when the fuel level gets low?

[DamnHippie]

OL stands for Open Loop, no continuity in the circuit. But that's just a way of restating the main text of the code.

[CHAVEZ]

No this was happening before it was replaced. I noticed the code after i fixed a different code that's been on for over 3 years. And yes the light would come on if the fuel was low. I just thought that by having this recall done it might fix the problem but it hasn't. this is really driving me nucking futts!

[CHAVEZ]

That makes sence but I can't figure out where the "open" circuit is.

[CHAVEZ]

it's back in the shop. I can't figure it out and it needs to be registered. apparently you can't have the ses light on at all or else it's an automatic fail. I guess they are having a hard time figuring it out also.

[Packman5280]

my pathfinder has had the check engine light on for 7 years, never once had trouble with passing the e-test. it was a rule at one time, but not anymore according to the air care colorado website and a call to the test center.

[Packman5280]

from the air care colorado website

"Check Engine Light

This is a malfunction indicator and/or maintenance reminder light, depending on make and model of the vehicle. It may say "check engine," "service engine," or "emissions," or may simply contain an image of an engine. A malfunctioning check engine light is noted on the vehicle inspection report each motorist receives at the end of the emissions testing procedure. However, effective April 1, 2003, it is no longer a criteria for failing the emissions test. This is now advisory only."

[CHAVEZ]

Ya I wish they were a little more lax on that here.

[Packman5280]

ah crap, didn't even realize you weren't in CO. oops.

[Sully4x4]

Can you pass emissions if your catalytic converter is goin out?

[DamnHippie]

It depends on how bad it's "going out". If it's not converting enough CO to CO2 and/or NO to N2 + O2, the test equipment will notice that and fail you.

[DamnHippie]

On the original problem, I had a look in the xterra FSM this morning, just in case the wording was misleading somehow on that P1464 code. I figured looking at the diagnostic procedure Nissan gives its techs might be enlightening.

In a way, it was enlightening: the wording turns out to be extremely precise. The ECM can detect a fault in the ground wire from the fuel level sensor to the ECM, but it can't detect a fault in the other wire. That is, the fuel level reads as 0 - 4.8 volts. If the reading is zero, it might be because you're out of gas, or it might be because the ground/return wire to the ECM is bad. It can sense the latter by comparing the reading on that wire to chassis ground.

Making it more interesting, it appears from the wiring diagram that the gauges on the panel don't use that same return wire, they just use chassis ground, so your gauges can be working fine and you still get that fault code. (What doesn't make much sense to me is why the ECM cares about the fuel level if it's isn't using the info to drive the gauges.)

Anyway, the diag procedure is to measure continuity from pin 66 of the ECM harness connector to ground. If there's no continuity at that point, that confirms the ECM's diagnosis/code. What I didn't figure out (ran out of time and had to leave for work) is just where on the body/frame that common ground point is for the fuel sensor, because it seems to me that corrosion on that connection (which is probably back near the tank somewhere) is a good candiate for this problem.

[CHAVEZ]

well i got my xterra back with the diagnosis that it needed a new ecm. I bought one from a bone yard in california and had it shipped here. works fine now code is gone.

[OdiN]

Well of course the code is gone in a different ECU :P

If it comes back, then what?

[nissandoms47]

Thats good you got it fixed. Hows the xterra doing anyways? Did you put all those new parts on I got for ya?

[Allen Cox]

Just to answer your question Ian. The ECU uses the information for emissions purposes. If it knows how much fuel is in the tank, then the computer can calculate the amount of fumes and pressure in the tank as well, since it also has a fuel temp sensor in the tank (located at the bottom of the sending unit). The fuel gets heated up by the engine, as it goes into and out of the fuel rail itself. Using all of that information, the computer then looks at the evap pressure sensor to see if the correct amount of pressure builds up when the computer shuts the vent control valve on the charcoal canister. If the pressure doesn't build up fast enough, there's a leak in the system. Depending on how big a leak will depend on the code thrown. A loose gas cap can be a big leak, a barely cracked rubber line can be a small leak. A bad vent control valve can also be a large leak, if the electrical portion is still good. Nissan had trouble with rust on the pintle shaft of their vent control valves. This would cause the valve to not close properly, causing a leak during diagnosis but not cause a vent control valve code because the electrical circuit was still good.

Ah, the over-complication of the automobile!

[CHAVEZ]

hey alex! ya i put that stuff on a long time ago thanks again. i'm trying to get a few things taken care of on it then i'm going to sell it for cheap, i'm getting sick of it.