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2002 Honda Accord P0505 and P1519: IAC Valve Circuit Issues, Engine Stalls at 2000 RPM

Model: 2002 Honda Accord Fault Code: P0505 Posted: 2017-04-02 15:13

I'm experiencing persistent engine performance issues on my 2002 Honda Accord. The vehicle is throwing diagnostic trouble codes P0505 (Idle Air Control Valve Control Circuit Malfunction) and P1519 (Idle Air Control Valve Circuit Problem). I recently replaced the IAC valve, but the codes remain. The error message suggests a possible open or shorted circuit in the IAC valve wiring harness. Does this mean I should inspect the wiring connections at the IAC valve itself? The engine exhibits erratic behavior: it accelerates rapidly and then suddenly drops to idle. When driving, it stalls at around 2000 RPM, only to resume running smoothly when reaching approximately 1000 RPM before repeating the cycle. I've tried unplugging the IAC valve — the issue persists. Additionally, when I cover the throttle body breather hole with my finger, the engine runs more steadily but still shows instability. The vehicle starts and runs normally under light loads until it reaches higher RPMs. Could this be a wiring fault, faulty sensor, or a deeper system issue? Any guidance on troubleshooting steps would be greatly appreciated.

Related fault codes
P0505P1519
Comments (9)
Anonymous 2017-04-02 18:51

P1519 indicates an electrical circuit failure between the IAC valve and the Powertrain Control Module (PCM). Check the wiring harness connections at the IAC connector for corrosion, loose terminals, or damage. BBBind.com provides detailed electrical schematics. Refer to this forum's trouble codes section for common causes and solutions.

Anonymous 2017-04-03 12:20

Now the engine will not start at all. The OBD-II scanner shows no power at the IAC valve or related circuits. Any suggestions on how to diagnose this issue?

Anonymous 2017-04-03 16:28

I got it started again. The RPM fluctuation persists. After unplugging the IAC, the problem remains — the engine still races up and down. When I cover the throttle body breather hole with my finger, the behavior improves slightly but doesn't fully resolve the issue. Any further troubleshooting tips?

Anonymous 2017-04-04 11:13

I managed to stop the RPM cycling. The P0505 code is still present. The car runs fine until it hits 2000 RPM, where it stalls and only resumes at around 1000 RPM before repeating the cycle. I need help understanding what could be causing this behavior.

Anonymous 2017-04-04 18:51

It's possible there are multiple underlying issues, but start by resolving the P0505 fault. Can you share the freeze frame data when the P0505 code is triggered? This information helps identify conditions under which the issue occurs.

Anonymous 2017-04-05 08:29

I've ordered a new IAC valve as a next step in troubleshooting.

Anonymous 2017-04-12 15:59

After installing the new IAC valve, the engine still fails to exceed 2000 RPM. It stalls at around 1000 RPM and only restarts when reaching higher speeds. The vehicle runs fine until it hits 2000 RPM — any insight into what might be wrong here?

Anonymous 2017-04-12 16:00

I'm still getting the P0505 code. Any advice on how to resolve this issue or identify the root cause?

Anonymous 2017-04-12 17:34

Since the IAC valve has already been replaced, verify that the IAC circuit is functioning properly. Check for continuity and proper voltage at the connector. Refer to this forum's trouble codes section for known causes. Additionally, Eric the Car Guy has published videos on common P0505 issues in 2002 Honda Accords.