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Severity: Moderate Code type: Manufacturer-specific (Honda)

Honda P1519 Code: Idle Air Control Valve Circuit Malfunction

The PCM found a fault in the idle air control valve (IACV) circuit on a Honda with a cable throttle.

At a glance

Severity: 3/5 – Moderate3/5

Severity: Moderate

Meaning
Idle Air Control Valve Circuit Malfunction
System
Speed & Idle Control · Powertrain
Safe to drive?
With caution
Typical repair cost
$10–$450
DIY difficulty
Moderate

Hondas with a cable-operated throttle, such as the 2001-2005 Civic, early-2000s Accord and CR-V, and the first-generation Fit, control idle speed with an idle air control valve that lets a measured amount of air bypass the closed throttle plate. The PCM powers the valve through the PGM-FI main relay and pulses the control side to set its opening. P1519 means the PCM saw a voltage on that control line that doesn't match what it's commanding: an open or shorted coil, a broken wire, missing power, or a valve so gummed up that it can't respond. Unlike a plain idle-speed code, this one points you to the valve's wiring and coil first.

Can I keep driving? The car can usually be driven, but idle may be too high, too low or unstable, and stalling when you come to a stop is possible. Be ready to restart and keep extra distance in traffic until it's fixed.

How to read P1519

How to read P1519P11253194
  1. P Powertrain
  2. 1 Manufacturer-specific
  3. 5 Speed, idle & inputs
  4. 19 Specific fault

Symptoms

  • Idle speed stuck high, often around 1,500 rpm or more after warm-up
  • Idle too low or stalling when stopping or when the A/C kicks in
  • Hard start or stall on cold mornings because fast idle is missing
  • Idle hunting up and down
  • Check engine light on

Possible causes

Ranked by how often each cause is behind this code (editorial estimate).

  1. IAC valve coil or internal driver failed 38%
  2. Corroded connector or broken wire at the IAC valve 22%
  3. No supply voltage from the PGM-FI main relay or fuse 14%
  4. Valve heavily carbon-fouled and sticking 12%
  5. Harness damaged or left unplugged after intake or throttle body work 8%
  6. PCM IAC driver fault 6%

Diagnosis step by step

Diagnostic flow: P15191Confirm and watch the IAC command2Check power at the valve3Check the control wire to the PCM4Inspect and clean the valve5Replace and relearn idle

  1. Confirm and watch the IAC command

    Clear the code and let the engine idle. On a scan tool, the IACV command should change when you switch on the headlights, blower and A/C; if the code returns immediately, the fault is electrical and constant.

    Tools: OBD-II scanner

  2. Check power at the valve

    Unplug the 3-pin IACV connector (older models use 2 pins). With the key on, one pin should show battery voltage from the main relay and one should have good continuity to ground. No voltage sends you to the fuse and main relay, not the valve.

    Tools: Multimeter

  3. Check the control wire to the PCM

    With the battery disconnected, test continuity of the IACV signal wire to the PCM and check that it isn't shorted to ground. Flex the harness near the throttle body while measuring, since this area moves with the engine.

    Tools: Multimeter

  4. Inspect and clean the valve

    Remove the valve from the throttle body or intake and look for heavy carbon in the air passage. Light cleaning with throttle body cleaner can free a sticky valve, but Honda treats a valve that set a circuit code as a replacement part.

    Tools: Screwdriver, Soft brush

  5. Replace and relearn idle

    After fitting a new valve, clear the code and let the PCM relearn idle: with all accessories off, start the engine and let it idle without touching the pedal until the radiator fan cycles, then check idle with loads on.

    Tools: OBD-II scanner

Where the parts are

Ignition: coils and spark plugs per cylinder – P15191234567
Ignition: coils and spark plugs per cylinder
  1. 1Ignition coil
  2. 2Spark plug
  3. 3Fuel injector
  4. 4Camshaft sensor
  5. 5Crankshaft sensor
  6. 6Engine computer (ECM)
  7. 7Intake manifold

Repair options & costs

RepairDIY?Estimated cost
Clean IACV and air passages Yes $10–$120
Replace IAC valve yourself (part) Yes $90–$250
Replace IAC valve at a shop No $200–$450
Repair IACV wiring or connector No $80–$250
Replace PGM-FI main relay Yes $40–$150

Rough US estimates for parts and labor; shop rates vary by region. Not a quote.

Emissions / smog test impact

Will fail

P1519 keeps the check engine light on, so the car fails an OBD emissions check, and a stuck-high idle can also look bad on older tailpipe-test programs. Complete the idle relearn and a few drive cycles before retesting.

Frequently asked questions

Can I just clean the IAC valve to fix P1519?

Sometimes a stuck, dirty valve comes back to life, but P1519 is a circuit code, so the coil or wiring is more often at fault. Honda's procedure is to test the circuit and replace the valve rather than clean it.

Why is my idle so high with P1519?

When the PCM can't control the valve, it may sit partly open and let extra air bypass the throttle. Idle then stays high even when the engine is fully warm.

Do I need to relearn idle after replacing the valve?

Yes. Without a relearn, the PCM keeps the old values and idle can hunt or stall for a while. Letting it idle undisturbed with accessories off until the fan cycles usually does the job.

What's the difference between P1519 and P0505?

P0505 is the generic idle control code and can mean anything from a vacuum leak to a sticking valve. P1519 is Honda's own code for the IAC valve's electrical circuit, which narrows the search to the valve, wiring and power supply.

Sources