Car keeps stalling codes: P1298 and P0700

Tiny
KEN L
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I have seen this before, it is strange, I don't think cleaning the IAC motor will fix it but you can try. Did you clear the codes? and if so do you have new codes? IF could be he EGR valve is stuck open, I would remove it and use this video.

https://www.youtube.com/watch?v=DqUCbbKdWf4

let me know what happens.
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Friday, December 26th, 2025 AT 9:29 AM
Tiny
AKORD
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I don't have any codes. Can I test the EGR valve with a smoke machine?
This EGR valve is a harness connection, not a vacuum.
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Friday, December 26th, 2025 AT 9:40 AM
Tiny
KEN L
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Yep, try cleaning the IAC valve and yes a smoke machine can help test the EGR.
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Friday, December 26th, 2025 AT 9:58 AM
Tiny
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This is an EGR valve. There was smoke coming out when I did a smoke test with a smoke machine.
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Friday, December 26th, 2025 AT 10:00 AM
Tiny
AKORD
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Probably the code P1399, got cleared because I disconnected the ground terminal when I changed the distributor cap and the spark plug wires.
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Friday, December 26th, 2025 AT 8:33 PM
Tiny
KEN L
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Yep, that valve is leaking good find. Yes, some codes will reset when the battery is disconnected.
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Monday, December 29th, 2025 AT 9:02 AM
Tiny
AKORD
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Hi Ken,

I cleaned the IAC valve. Right now, the car is idling properly.
Thank you for the help, Ken.
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Wednesday, January 14th, 2026 AT 3:59 PM
Tiny
KEN L
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Glad you could get it fixed, thanks for letting us know. Please use 2CarPros anytime we are here to help. Ken
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Thursday, January 15th, 2026 AT 10:59 AM
Tiny
AKORD
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Hi Ken,

I drove the car but it hesitated when accelerating, and the car stalled a couple of times when I was driving it.
Do you think the IAC valve is faulty?
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Thursday, February 12th, 2026 AT 5:49 PM
Tiny
KEN L
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Yep, it sounds like it IAC is failing intermittently.
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Friday, February 13th, 2026 AT 8:38 AM
Tiny
AKORD
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I replaced the IAC valve with an aftermarket one, and the idle is around 750, but when I press on the gas pedal, the RPM fluctuates, then did a smoke test, and the smoke was leaking from the top of the IAC.
Do you recommend using RTV, and thread sealant on the bolts?
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Friday, February 13th, 2026 AT 2:20 PM
Tiny
KEN L
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The O ring should seal it, did you replaced it or does it have one? Also, if you press the brake pedal and it effects the engine you may have a leaking booster. I would remove the vacuum line check valve of the booster and if no vacuum escapes the booster is bad (engine off).
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Saturday, February 14th, 2026 AT 8:35 AM
Tiny
AKORD
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I installed the old IAC valve back with a new o ring, and did a smoke test, no leaks. I started the car, when I pressed the gas the rpm was fluctuating, I could not hold at a certain RPM, then the car shut off, did not start after that, just a crank no start.
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Saturday, February 14th, 2026 AT 9:59 AM
Tiny
AKORD
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**Ignore the last reply. I was going to delete the last reply, but I couldn't.

So I put the new IAC valve, the car started at about 1k RPM, ( the old one was 2k RPM, then dropping to 750 RPM). The car lost coolant, so I added I was burping the coolant while the car was running. But the car, before reaching the operating temperature, the fan did not kick on, and the engine stalled. The car did not start again.

Do you think the new IAC is bad?

*I checked the brake booster when I disconnected the line, the vacuum escaped from the booster.
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Saturday, February 14th, 2026 AT 5:25 PM
Tiny
KEN L
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That is a good sign the booster is okay. Listing to the video again it seems like the engine still has a vacuum leak. Please go over this video and guide to help us fix the problem.

https://www.2carpros.com/articles/stall-at-idle

and

https://www.youtube.com/watch?v=LRKWV4Are5c

Please go over these guides and get back to us.
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Sunday, February 15th, 2026 AT 9:15 AM
Tiny
AKORD
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After replacing the IAC valve check the engine light came on (P1519 and P0505). I held the RPM at 3000 according to the service manual for a couple of minutes and the engine stalled, then I tried to start again, but it didn't start, my second attempt I had to press the gas pedal to help the car to start, and the car started for a minute or so then stalled, I tried to start again but it didn't start.

I did a smoke test ( key OFF, engine OFF)looks like there is a leak coming from the IAC valve connector.
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Thursday, February 19th, 2026 AT 7:20 PM
Tiny
AKORD
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IAC valve leaking

*Can I smoke test the intake with the key ON and the engine OFF?
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Thursday, February 19th, 2026 AT 7:22 PM
Tiny
KEN L
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Wow, that is the problem you have a massive vacuum leak, It may be leaking below the IAC like a PCV hose, I would use a small mirror and flash light to pin point the leak, this is the source of the issue. Thanks for the video it helps, let me know what you find. Ken
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Friday, February 20th, 2026 AT 9:00 AM

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