The Quick Answer above is the generic definition. What follows is the model-specific detail for the Honda models that log P0508.
DTC/P0508·Honda
P0508 on Honda: Causes, Symptoms and Fix Cost
Quick Answer
Moderate SeveritySafe to drive (short-term)Honda
P0508 on a Honda means the ECU is detecting a voltage on the idle air control valve circuit that is below the expected threshold. A usual cause is a short to ground in the wiring, but a failed valve coil or a corroded connector can produce the same symptom. This code applies to vehicles with a separate idle air control valve rather than fully electronic throttle bodies.
Typical repair cost, all makes€45 - €1000
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Honda Civic
2001-2011Honda Civics with the K20 use an idle air control valve that is generally reliable but can suffer wiring damage from the intake harness rubbing on the throttle cable bracket. The signal wire shorts to ground intermittently and the ECU sets P0508. The later R18A is drive-by-wire and has no separate valve, so on those cars look at the electronic throttle circuit instead.
What causes P0508 on a Honda?
Beyond the generic causes listed on the main P0508 page, these are the patterns noted for Honda models:
Honda CivicWiring short from chafing at the throttle cable bracket on K20
Honda CivicElectronic throttle circuit fault on drive-by-wire R18A engines
How to diagnose P0508 on a Honda with OBD2
Follow these steps to pinpoint the root cause of P0508:
- Read freeze-frame data and confirm the ECU sees the IAC circuit below threshold at the time of the fault
- Locate the IAC valve (usually mounted on or near the throttle body) and inspect the connector for corrosion, oil mist, and damaged pins
- Unplug the valve and measure resistance across the coil terminals and compare it with the manufacturer specification, which differs widely between valve types. A reading well below spec confirms a shorted coil
- With the valve unplugged, measure resistance from each connector pin to chassis ground. A near-zero reading on the signal wire indicates a wiring short
- If wiring and valve test good but the code returns, suspect the ECU driver circuit. Confirm with a known-good spare ECU before condemning the original
How much does P0508 cost to fix on a Honda? (EUR)
Estimated repair costs for P0508 in EUR, compiled across makes. Honda parts and labour usually land towards the lower end of each range.
Prices estimated as of March 2026. Costs vary by region, vehicle, and shop.
Codes related to P0508
These codes are often seen alongside P0508 or point to related issues, on any make:
Looking for the full P0508 reference (all makes, full diagnosis flow, complete repair cost matrix)?
See the main P0508 guideSkanyx · Honda
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