2003 Kia Sedona van dying

OK, this is my sister in law’s van. She has done very little in way of maintenance as far as I can see. Currently, it is sitting in my driveway where it has for the last 4 to 5 months, and I am looking for any ideas on problems to get it out of my way before winter…

When it first got here, it would go about 20 miles an hour and never more, even with foot to the floor… We changed plugs wires oil and fuel pump… Still same problem… Now, however, when we idle it, it runs real rough, and when you try to back up, it dies, then you can not restart. It has plenty of battery, because if you leave it overnight, it will start again, but dies if you try to back up…

Can honestly say. I don’t know if first problem is fixed as we can’t get it out to test drive… We have added some fuel injector cleaner thinking it clogged after sitting for so long.

It has sat so long as we fixed things when she had the money, and it was summer, so not a big deal…

Any helpful ideas??

Why did you replace the fuel pump? Was this a guess or did you check the pressure with a gauge? Either way, checking the fuel pressure is a must.

Did it get a new fuel filter? How about an air filter?

If you have a vacuum gauge you can check it for exhaust blockage. If you don’t try pulling the front O2 sensors and see if that makes any difference.

we replaced fuel pump as we also thought of the fuel filter being clogged however the nice little filter is in the pump so it got a whole new pump

ok gang I broke down and got a computer scanner. the code it came up with was for a intake air temp sensor but no auto part store has one… where do i get one??

You would call Kia. Or use the internet to find one. Tons of parts on the internet. There’s little that you can’t get from rockauto.com, for example.

Do you even put a fuel pressure gauge on it? Check for exhaust blockage?

No code will tell you that a sensor is bad. What was the exact code? (e.g. “P1234”)

An intake air sensor is not going to cause a vehicle to be anemic.
I’d suspect a large vacuum leak or a clogged catalytic converter. A vacuum gauge should reveal if either one of these conditions exist.

FWIW, Would A Bad TPS (Throttle Position Sensor) Cause All These Symptoms ?

Does this vehicle have a 3.5L engine ?

A Kia Technical Service Bulletin (written for Kia technicians) indicates that TPSs on 2002 - 2005 Sedonas with the 3.5L engine can have TPSs that go to hxxl in a hand basket (suffer from excessive wear of inner elements).

My bulletin won’t load properly (I can only read the majority of it), but there should be a DTC PO121, PO122, and/or PO1xx [?]. I notice these codes are close in appearance to the one that toni5915 has probably obtained.

The fix is an apparently revised Kia TPS. The 4 page bulletin is #KT2007040401 (4/4/2007).


I will try to answer all of these questions… first it is a 3.5 tried to get to the bulletin above but cant? How did you get to it maybe I am doing something wrong there… Dont have a vaccuum gauge but did pull the o2 sensor and no change in it… we did take the mass air flow sensor off and it idles and when we put it back in the van immediately died. finally the computer code when i looked it up said " High Intake Air Temp" which is why I was thinking this sensor… Keep giving me answers I will keep trying…I am just a backyard mechanic trying to help my sister with this one…

You still need to report the actual, specific code. The “high” in the code description will not refer to high temperature. It will refer to high voltage. E.g. the code P0113 just means that the PCM saw an air intake voltage higher than 5V. This is bad b/c the PCM only ships the sensor 5V - the sensor then returns anything from about .5V to 5V depending on the air temperature. (More voltage back if hotter).

But as ok4450 noted, this shouldn’t give the symptoms you have. First, hook up the code reader again and 1) write down the exact and specific code to post; 2) double check that this is your only code.

Note that your IAT sensor is integrated with the MAF sensor. I think it is replaceable as a separate component, but the first thing to do is carefully inspect all of the wiring that goes to the MAF/IAT. Ideally you also have an electrical meter and can do some testing of the circuit/sensors.

ok thanks for all but it will be sat before i post again and have time to look at it some more

well I managed to get off work early and played with this van again… first i plugged back in the o2 sensor, cleared all codes on computer and rescanned… only thing that came up was po123 throttle/pedal position sensor/switch a circuit high. what’s our best guess???

At this point, I would probably replace the main battery cables, both positive & negative (at almost 10 years old you can’t really lose on that) and then find every grounding point under the hood, pull them all, clean them up and reattach. Then I’d see where things stand. I say that just on the idea that if I had codes that seemed to indicate voltage problems and were moving targets then I’d first suspect a bad ground.

I’d still check the fuel pressure too though.

Did This Car Spend A Lot Of Time In A Hot Climate ?
This could be an important clue.

we live in Iowa so extreme hots and extreme colds

That TPS Technical Service Bulletin I Referenced Earlier Described A Problem Found In Vehicles In Hot Climates, Especially. Now You Have A TPS DTC (Code).

Since you’re trying to DIY and keep costs at a minimum, I’d bop over to a local Kia dealer and befriend the Service Manager/Service Director (or if need be, the Parts Department guys) and have them pull that bulletin for you. Discuss this issue with them and see what they think. They might have some experience with this that they will remember.


If the vehicle were mine I’d put a vacuum gauge on it and make sure there’s not a clogged converter problem before spending one dime on anything.

I’m with ok4450 on completely ruling out a plugged catalytic converter before doing much else. Usually, pulling an upstream oxygen sensor will allow enough exhaust pressure to escape to make a significant difference, but may not have in this instance. A vacuum test is definitive in diagnosing this, but another tool-free test, although not entirely definitive, is to rev the engine while in park. If the engine falls flat on its face at a rather low engine speed (probably under 2k RPM from the sound of things) and sounds somewhat like a vacuum cleaner, there’s a very good chance the catalytic converter is clogged.