2007 Hyundai Santa Fe - Misfired for five years

Occasional misfire (5 Years) then resumes without difficulty, check engine code- low voltage. Usually disappears on its own. Never fails otherwise. Replaced battery, terminals, gas tank sensors, cleaned grounds, replaced gas cap, cleaned computer connectors. Occurred at 35,000 to now 50,000 miles 2007 Hyundai Santa Fe 3.3 Any suggestions ?

Yeah, POST the check engine code you got - the Pxxxx code, not just the description.

Is your current mileage 50K? Or more? Seems very low for a 12 year old car but…

Why have you put up with this for 5 years and now you want to fix it? Did you ever have a mechanic try and find the problem? If not, why not? Are you going to try and fix it yourself?

Did you do this work yourself? Why did you choose to do these tasks? In other words, did you diagnose the problem and find the car needed a battery? new gas tank sensors? a new gas cap? Or was this just a failed attempt to fix the problem?

Help us out here, there is LOTS of history here and it is all helpful to finding a solution.

Car used only for short trips, a certified mechanic did all the work— all failed,The car functions perfectly and may go 2-3 months without a problem. Admiitedly it dosen’t travel much. I’ve forgotten the code, but it was the same each time by me and my mechanic and it was low voltage hence the electrical work. For a time I and my mechanic believed it was the gas cap --not so. I will work on it myself if possible. since I have over 60 years doing auto work

And bt the way THANKS

That narrows it down to about 600 possibilities

We will need the exact code.

1 Like

Seems like your mechanic was throwing parts at the car trying to find the cause rather than diagnosing it. Maybe look for a better mechanic. One comfortable with computer controlled cars that owns and knows how to use a scanner to read data off the car.

That’s the best help I can give you seing as how you didn’t tell us the mileage, or the error codes.

Not so–we discussed the problem and the possible fix.-- He has been a personal friend for 40 years. The mileage was given. It is 54, 000 and the code repeated exactly the same perhaps 15 X was low voltage THANKS FOR YOUR THOUGHTS .

Low voltage is not a code.


Friend or not, if he really believed that a gas cap could in any way affect voltage, you really need a new mechanic.

1 Like

My idea on the first go around, and later with the P2507 code the electrical .

Now narrowed to the computer its connector, or the harness wires themselves. Just a matter of where to start since it is somewhat complex --anybody with experience or suggestions.

Something I’ve run into a few times is a fault in a wire in the harness. Checks with an ohmmeter will show continuity but the wire is still faulty.

A check needs to be done with a load applied to that wire. Meaning the use of a test light at a minimum. The PCM connector needs to be disconnected from the PCM and probed with the test light. If the bulb is dim then it could be that wire has an internal fault.

The few times I’ve seen this I snipped the wire out of the harness and replaced it with a new piece of wire. It cured the problem.

5 Years? Why?

Because it rarely happened–now more frequently, about 1x a month on average, sometimes not for 3 months. And because it’s lasts for a second or two and resumes normally-Not worth all the effort to clear it up then. Now it’s changing.

THANKS–that was my plan, but I waited for one who had experienced the same.

This sort of problem w/a wiring harness can be difficult to find. Not auto related, but a place I worked had a customer’s machine, a special purpose computer about the size of a fridge go on the fritz. It took 2 field service staff 4 entire days to figure it out. A tiny bit of wire, about 1.5 mm long, had lodged under a connector, invisible to see without desoldering the connector, and would intermittently short two pins out. And they were two highly trained and experienced electronics technicians with all the diagnostic equipment and the entire engineering department on call to help with providing design documents and ideas.

THANKS George. And for all who commented, that is why I have been hesitant all this time. A lot of time and patience is needed for such a problem that lasts a couple of seconds and seems to disappear for a time.

1 Like

The first time I ran into a wire glitch like this involved a VW. It was towed in 3 times in 2 weeks for just dying and not restarting. Once on our lot it would start right up with no problem and run like a top. Test drives were fine, no codes set, etc.

The 4th time it was towed in it would not start. No spark. Ok. Now this will be easy. Not. Tests were done a a dozen times and testing showed everything was fine. This became a parts swapping thing which is something I loathe BUT the factory service manual stated to do this. New ignition module. No spark. New distributor. No spark. Power out of the ign. switch fine. No spark. VW factory rep came around about this time and threw up his hands after an hour or so.

That night at home I decided wire harness. It had to be. So next morning I took the wire cutters and went to work; cutting out every wire in the harness after double checking again. Spliced in new wires, it fired right up, and never was a problem again.

(As for the module and dist. the customer was not charged for this. They were given back to the parts dept. and his originals reinstalled.)

1 Like

THANKS sometime the obvious is not so and with all the responses, I’m in a way happy others have agreed with us. My issue is more than 5 years old and is so infrequent I’m in low gear about it, but I know where to go .

1 Like