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Codes P0088, P0306, P0305, P0300 and P0304?

Tiny
MYMOUNTAIN
  • MEMBER
  • 2021 KIA SEDONA
  • 3.1L
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 122,000 MILES
Changed all six plugs and one bad ignition coil, new battery, changed two Co2 sensors. Sprayed starter fluid around hoses, no vacuum leak, changed gasket when doing back plugs.
Idles great until you step on gas, misfires and won't go over 2,000 RPMs. Thinking not fuel since it won't go over 2,000 RPMs. I've attached the live diagnostic readings.
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Thursday, December 14th, 2023 AT 4:24 PM

13 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,644 POSTS
Hi,

I looked at the pics you attached. What is the ambient temperature where you are located? I ask because there "appears" to be a variance between the intake air temperature and the coolant temperature sensor.

I'm seeing -40 and then 30 C (ECT) and 2 degrees C for the intake air temperature. I'm not familiar with the scanner, so could you clarify that for me?

Let me know.

Joe
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Thursday, December 14th, 2023 AT 8:58 PM
Tiny
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Cold here. I think it was 40 degrees when I took that reading and less night before.
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Thursday, December 14th, 2023 AT 9:13 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
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Do the temperature readings make sense to you? We may be getting a very rich or very lean fuel mixture if the ECT is off. Which one seems accurate?

Joe
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Thursday, December 14th, 2023 AT 9:22 PM
Tiny
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  • 51 POSTS
Okay, new data new codes. Outside temp 37 degrees. Warmed van up so the temp gauge was 1/2 way. Idol was great. Press gas no hesitation or skip. Backed up smooth, put in gear and pressed gas no power. After trying to drive the traction control light came on the dash, pressed button and it wouldn't go off.
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Friday, December 15th, 2023 AT 8:27 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
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Have you confirmed the fuel pressure is within the manufacturer's specifications? It could be an issue with the fuel pressure control valve. It's located under the intake. See pics below. Pic 1 is the control valve and pic 2 is the pressure sensor.

Let me know.

Joe

See pics below.
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Friday, December 15th, 2023 AT 11:13 PM
Tiny
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#1 is attached to Fuel Pump - Kia (35320-3L110). I don't think the control valve comes out of the pump. Looks like all one piece. That solves #1 identification. Now for #2.
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Saturday, December 16th, 2023 AT 7:41 AM
Tiny
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Hi,

You are correct. Number 2 in the pic is under the intake manifold.

Joe
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Sunday, December 17th, 2023 AT 5:57 PM
Tiny
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Before I spend $350.00 on #1 is there a way to narrow it down? I think you said fuel rail pressure test.
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Sunday, December 17th, 2023 AT 6:03 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
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Hi,

The directions (pics 1 - 4) are testing pressure from the low-pressure pump in the tank. The high-pressure pump should be done using a scan tool. The pressures are extremely high. See pic 5 below.

Let me know.

Joe
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Sunday, December 17th, 2023 AT 6:56 PM
Tiny
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One take from another mechanic. What do you think? We might be barking up the wrong tree, the P0088 code "Fuel Rail/System Pressure - Too High." Which means the high-pressure pump pressure regulator has gone bad or the sensor is bad. Let's try replacing the sensor and if that doesn't help the high-pressure pump will need to be replaced. Here are the instructions to help us fix the problem. Check out the images (below). Please let us know what happens.
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Tuesday, December 19th, 2023 AT 1:01 PM
Tiny
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Hi,

You could be correct, and we appreciate your input. Let's see what he thinks.

Take care and thanks for your input.

Joe
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Tuesday, December 19th, 2023 AT 9:05 PM
Tiny
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Hey, I wanted to follow up and thank you for all your help! It turned out to be the high-pressure fuel pump after changing everything else out. Just recently I got a warranty extension letter from KIA on a defective high pressure fuel pump that they would replace for free. Sent them a $1,200 bill, will see if they pay it.
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Sunday, August 4th, 2024 AT 8:14 PM
Tiny
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Hi,

Thank you for the follow up. It's appreciated. I'm glad to know you resolved the issue. I suspect Kia will reimburse you, but they aren't fast about it. LOL

Regardless, thanks again and feel free to come back anytime in the future.

Joe
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Monday, August 5th, 2024 AT 8:15 PM

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