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DTC/P0506

P0506: Idle Air Control System RPM Lower Than Expected

Quick Answer
Moderate SeveritySafe to drive (short-term)Fuel System

P0506 means the engine is idling at a lower RPM than the ECU expects, typically 100 RPM or more below target, and the ECU cannot bring it back up. The opposite of P0507, this code is usually caused by carbon buildup on the throttle body restricting airflow, a partially clogged idle air control passage, or a vacuum hose pinched or blocked rather than leaking.

Estimated repair costFrom €5 to €550+, varies by vehicle

What does P0506 mean?

P0506 means the engine is idling at a lower RPM than the ECU expects, typically 100 RPM or more below target, and the ECU cannot bring it back up. The opposite of P0507, this code is usually caused by carbon buildup on the throttle body restricting airflow, a partially clogged idle air control passage, or a vacuum hose pinched or blocked rather than leaking.

P0506 is a fuel system-related diagnostic trouble code classified as moderate severity. When your vehicle's ECU detects this condition, it stores P0506 and illuminates the check engine light.

What are the symptoms of P0506?

If your vehicle has triggered P0506, you may notice one or more of these symptoms:

  • Idle noticeably lower than normal (500 RPM or less)
  • Engine stalls at idle or when coming to a stop
  • RPM dips and recovers when the AC compressor engages
  • Rough or shaky idle with the engine in gear (automatic)
  • Check engine light on

What causes P0506?

Here are the most common causes of P0506, ranked by how likely they are to be the culprit:

highCarbon-fouled throttle body restricting airflow at idle
highClogged or stuck idle air control valve
mediumBlocked PCV passage or restricted idle air bypass
lowFaulty coolant temperature sensor causing wrong idle target

Is it safe to drive with P0506?

Generally yes, for short-term driving. The engine idles lower than the ECU target and may stall at junctions or when the AC compressor engages. Drive cautiously and fix within a couple of weeks to avoid being stranded by an unexpected stall.

How do you diagnose P0506?

Follow these steps to pinpoint the root cause of P0506:

  1. Read freeze-frame data and confirm idle RPM at the time the code set. Compare to the ECU's commanded idle target shown in live data
  2. Remove the intake boot and inspect the throttle plate and bore for carbon buildup. Heavy deposits restrict airflow even with the plate fully closed
  3. Clean the throttle body with throttle body cleaner and a soft cloth. On electronic throttle bodies, do not force the plate open by hand; use the scan tool throttle test instead
  4. If equipped with a separate idle air control valve, remove and clean or test it with the scan tool to verify movement through its full range
  5. After cleaning, perform the manufacturer's idle relearn procedure. Without a relearn, the ECU continues to command the same restrictive throttle position

How much does P0506 cost to fix?

Repair costs for P0506 vary depending on the root cause and your vehicle. Here are typical estimates:

Repair Parts Cost Labor Cost Total Estimate DIY Difficulty
Clean throttle body €5–€15 €0–€60 €5–€75 Easy
Clean or replace idle air control valve €60–€200 €40–€100 €100–€300 Moderate
Replace throttle body assembly €150–€400 €60–€150 €210–€550 Professional

Prices estimated as of March 2026. Costs vary by region, vehicle, and shop.

P0506 on specific vehicles

P0506 behaves differently depending on your vehicle. Select your car below for model-specific causes, known issues, and adjusted cost estimates:

Toyota

P0506 on Toyota Camry

2002-2018

Older Camrys with the 2AZ-FE and 2GR-FE use an electronic throttle body that fouls with carbon over 80,000-120,000 km. Toyota's idle relearn after cleaning requires the engine to idle for five minutes with the AC off, all accessories off, and the throttle untouched.

What causes P0506 on a Toyota Camry?

Toyota CamryThrottle body carbon on 2AZ-FE and 2GR-FE
Toyota CamryPCV valve hose clog restricting idle air supply
Volkswagen

P0506 on Volkswagen Golf

1998-2010

Mk4 Golf with the 1.8T (AGU, AWP) is famous for idle air control valve coking. The valve sits on the side of the throttle body and the bore packs with carbon and oil mist from the PCV system. Cleaning often revives it but a replacement is usually needed before 200,000 km.

What causes P0506 on a Volkswagen Golf?

Volkswagen GolfIAC valve coking on Mk4 1.8T
Volkswagen GolfThrottle body throttle plate carbon on EA113

P0506 repair cost for Volkswagen Golf

Estimated costs for Volkswagen Golf ownersadjusted higher than average due to Volkswagen-specific parts pricing

Repair Parts Cost Labor Cost Total Estimate DIY Difficulty
Clean throttle body €6–€17 €0–€69 €6–€86 Easy
Clean or replace idle air control valve €69–€230 €46–€115 €115–€345 Moderate
Replace throttle body assembly €173–€460 €69–€173 €241–€633 Professional

Prices estimated as of March 2026. Costs vary by region, vehicle, and shop.

Ford

P0506 on Ford Focus

2005-2014

Mk2 Focus with the 1.6 Duratec is prone to a sticky electronic throttle body causing P0506 along with surging or stalling at idle. Ford has a known throttle body cleaning service procedure with a specific software-driven relearn that resets the adaptive idle values.

What causes P0506 on a Ford Focus?

Ford FocusSticky throttle plate on 1.6 Duratec
Ford FocusPCV breather hose collapse restricting idle air

P0506 repair cost for Ford Focus

Estimated costs for Ford Focus ownersadjusted lower than average due to Ford-specific parts pricing

Repair Parts Cost Labor Cost Total Estimate DIY Difficulty
Clean throttle body €5–€14 €0–€54 €5–€68 Easy
Clean or replace idle air control valve €54–€180 €36–€90 €90–€270 Moderate
Replace throttle body assembly €135–€360 €54–€135 €189–€495 Professional

Prices estimated as of March 2026. Costs vary by region, vehicle, and shop.

Honda

P0506 on Honda Civic

2006-2015

R18A Civics commonly log P0506 from a clogged IACV. Honda's recommended fix is to remove the valve, clean it with carburettor cleaner, and reset adaptations by disconnecting the battery for ten minutes followed by a ten-minute idle with the AC off.

What causes P0506 on a Honda Civic?

Honda CivicIACV carbon clogging on R18A
Honda CivicThrottle body bore deposits on 1.8 SOHC i-VTEC

P0506 repair cost for Honda Civic

Estimated costs for Honda Civic ownersadjusted lower than average due to Honda-specific parts pricing

Repair Parts Cost Labor Cost Total Estimate DIY Difficulty
Clean throttle body €5–€14 €0–€54 €5–€68 Easy
Clean or replace idle air control valve €54–€180 €36–€90 €90–€270 Moderate
Replace throttle body assembly €135–€360 €54–€135 €189–€495 Professional

Prices estimated as of March 2026. Costs vary by region, vehicle, and shop.

These codes are often seen alongside P0506 or indicate related issues:

P0505P0507P0508P0509P0171

Common questions about P0506

Why is my car idling so low?

Carbon buildup on the throttle body or a stuck idle air control valve is the most common cause. The engine cannot pull enough air at idle, the ECU cannot bring RPM up to target, and you feel it as a shaky, sometimes stalling idle.

Will cleaning the throttle body fix P0506?

Often yes, but only if you also perform the idle relearn afterwards. Without the relearn, the ECU keeps commanding the throttle to the position it learned when the bore was dirty, and the symptom returns within a day or two.

Why does my engine stall when the AC turns on?

The AC compressor adds load to the engine at idle. A healthy idle control system raises RPM to compensate. When P0506 is set, the system can no longer pull that extra air, so the engine loses RPM and may stall.

Is P0506 the opposite of P0507?

Yes. P0506 means the engine idles too low; P0507 means it idles too high. Both point to a problem with how the ECU controls idle airflow, but the causes are different. P0506 usually points to restriction; P0507 usually points to a leak or stuck-open valve.

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