Air intakeGeneric OBD-II codeUrgency: Garage soon
Code P0506: idle speed too low
P0506 means: idle air control system: idle speed lower than expected.[1][2][3] The control unit has detected that the idle speed is below the target and cannot correct it. As an example, AutoDTCs describes the speed being 100 rpm or more below the target for 7 seconds in a row, with the control unit unable to correct it even with the maximum idle compensation.[1][2]
What code P0506 means
The control unit has detected that the idle speed is below the target and cannot correct it. As an example, AutoDTCs describes the speed being 100 rpm or more below the target for 7 seconds in a row, with the control unit unable to correct it even with the maximum idle compensation.[1][2]
The sources give different references for normal idle: AutoDTCs gives 550 to 800 rpm (550 to 750 elsewhere on the same page) and PartsAvatar 750 to 1,000 rpm, with the code set when it drops below 750. The value depends on each manufacturer, and also on load and temperature.[1][2]
It applies both to engines with a separate IAC valve (open circuit, valve stuck closed) and to those with electronic throttle (dirty or damaged throttle body). Normally two failed journeys are needed to turn the light on, and three clean ones to turn it off.[1]
Original definition (SAE J2012): Idle Air Control System RPM Lower Than Expected[1][2][3]
Causes of P0506
From most to least likely, according to the sources.
- 1Throttle body with soot or carbon deposits, which reduces the idle air. On engines with electronic throttle and high mileage (AutoDTCs mentions more than 60,000 miles, almost 100,000 km), it is the most common cause.[1][2]
- 2Faulty or sticking IAC valve or motor, stuck closed, or the valve's supply circuit open or with high resistance, on engines that have one.[1][2][3]
- 3Vacuum leak.[2][3]
- 4Restriction in the air intake (blocked filter, collapsed duct, a foreign object), or blocked exhaust.[1][2]
- 5PCV valve or crankcase ventilation hoses blocked.[1][2]
- 6Faulty power steering pressure switch, which can make the speed drop when the steering wheel is turned.[2]
- 7Throttle stop screw badly adjusted, dirty mass airflow sensor or fault in the throttle control unit, according to CarWiki.[3]
- 8Internal engine problem or faulty control unit.[2][3]
Symptoms
- Irregular or clearly low idle with the engine warm.[1][2][3]Vibrations: faults that cause it
- The engine stalls when loads are applied (air conditioning, headlights, turning the steering wheel), when stopping or when manoeuvring at low speed.[1][2]Engine stalls: faults that cause it
- Hesitation when pulling away from a standstill, because the speed drops even further when the accelerator is opened.[1]
- Engine fault warning light on, which may not appear until the second failed driving cycle.[1][2][3]Engine warning light: faults that cause it
How to diagnose P0506
In order: from the most likely and cheapest to check to the most expensive.
- 1Read the other codes. AutoDTCs, following Jeep's procedure, advises resolving the throttle body codes first: P0121 to P0123 (position sensor), P2100 and P2101 (throttle motor) or P2176 (idle position not learned).[1][2]
- 2Look at the freeze frame data and compare the actual idle speed live with the manufacturer's figure. Load the engine with the air conditioning and the blower to see whether the control unit maintains a normal idle.[1][2]
- 3Check the air intake: dirty or collapsed air filter and the duct from the filter to the throttle body, looking for kinks or foreign objects.[1]
- 4Check the PCV: AutoDTCs proposes removing the valve and shaking it (if it rattles, it moves; if it does not rattle, it is stuck closed) and checking the crankcase hoses for collapse, cracks or blockage.[1][2]
- 5Inspect the throttle body and clean the bore and the throttle plate with a specific cleaner. AutoDTCs warns not to spray intake cleaner into an electronic throttle engine while it is running, and that the throttle must then be relearned with the diagnostic equipment. Also look for vacuum leaks and check the power steering pressure switch.[1][2]
- 6On engines with an IAC valve, disconnect it at idle: if the speed barely changes, the valve is stuck or not working; also check its power supply. On electronic throttle engines, check that the connector seats properly and inspect the wiring of the position sensor and the motor.[1]
Can I keep driving with P0506?
Garage soon
AutoDTCs rates it as moderate severity: it is not an emergency, but a low idle can cause stalling under load, and it is worth repairing within a week to avoid being stranded in traffic. PartsAvatar gives no overall rating, but notes that a faulty power steering pressure switch is a safety issue that should be addressed as soon as possible.[1][2]
Documented faults related to P0506
Known faults of specific engines and cars, with their repair cost, the affected years and their sources.
Carbon build-up in the intake: the most serious faults by engine and car
- Medium severityFrequency: Very frequent2.0 TSI / TFSICarbon build-up on the intake valvesBecause the fuel is injected directly into the cylinder, no petrol washes over the intake valves, so oil residue and soot build up and, over the years, restrict airflow and affect engine response.
- Medium severityFrequency: Common1.6 HDiLeaks at the injector washers and carbon build-up in the cylinder headIt is common for the copper washers of the 1.6 HDi injectors to stop sealing: the engine blows gases, carbon forms around the injector and soot gets into the oil. It is cheap to repair, but if left it contaminates the oil and is one of the causes of turbo failure.Repair (garage): €110–€310
- Medium severityFrequency: Common1.6 GDI / T-GDICarbon build-up on the intake valvesBeing pure direct injection, with no port injectors to wash the valves, the 1.6 GDI and T-GDI build up intake carbon with mileage: unstable idle, jerking or loss of power. A design trait of all direct injection, not a manufacturing fault.
- Medium severityFrequency: CommonMZR-CDCarbon on the injectors, EGR valve and intakeUrban use and short journeys encourage carbon to build up on the injectors, EGR valve and intake of the MZR-CD, with loss of power and jerking; documented on the Mazda6 and Mazda3, on both the 2.0 and the 2.2.
Engine sensors: the most serious faults by engine and car
- High severityFrequency: Occasional2.0 DTI and 2.2 DTIVP44 injection pump and air mass meter failureGerman Wikipedia documents recurring failures of the Bosch VP44 injection pump and the air mass meter in the early years of this engine. An owner testimony for this engine describes the pump being replaced at 192,500 km, at a cost the owner calls «prohibitive».
- Medium severityFrequency: Common2.0 TDIClogged particulate filter or faulty pressure sensorThe 2.0 TDI's particulate filter clogs if the car mostly makes short journeys, because it never gets to regenerate; sometimes the fault is just the differential pressure sensor. Cleaning it costs around €200 and replacing it, €800 to €3,000.Repair (garage): €800–€3,000
- Medium severityFrequency: Common1.4 and 1.6 8vCrankshaft position sensor failure (TDC sensor)The crankshaft position sensor (capteur PMH, or TDC sensor) appears repeatedly in the reliability sources for the Clio II, the Kangoo I and the Dacia Logan I with this engine, with hard cold starting or stalling as the main symptoms. It is a cheap part, but the failure can leave you stranded.
- Medium severityFrequency: Common1.4 and 1.6 16vCrankshaft position sensor failureThe crankshaft position sensor (capteur PMH) appears repeatedly in the reliability sources for almost every generation with this engine, with hard cold starting, stalling or the car cutting out unexpectedly. It is a cheap part, but the failure can leave you stranded.
Frequently asked questions
Can I drive with code P0506?
You can, but there is a risk of stalling under load or when stopping. AutoDTCs advises repairing it within a week. If the engine stalls often, take it to a workshop sooner.[1]
Does cleaning the throttle body fix it?
AutoDTCs states that, in most cases on modern engines with electronic throttle and more than 60,000 miles (almost 100,000 km), cleaning it and relearning solves it. This is the website's own claim, with no supporting data. Relearning after cleaning is essential.[1]
What is the normal idle speed?
It depends on the car. The sources give different references (550 to 800 rpm according to AutoDTCs, 750 to 1,000 rpm according to PartsAvatar), and the correct value is the manufacturer's, which also changes with load and temperature.[1][2]
What is the difference between P0506 and P0505 or P0507?
P0506 indicates idle below the target and P0507 above it; P0505 is the general idle control fault, without specifying the direction of the deviation. AutoDTCs lists P0505 and P0507 as codes related to P0506.[1][2]
Will I pass the MOT with code P0506?
If the code has switched on the engine warning light, no: with that light on, the inspection records a serious defect, and on Euro 5 and Euro 6 cars the ITV (Spain's roadworthiness inspection, similar to the MOT) also reads the OBD diagnostic system. Repair the fault before you go; clearing the code just before the inspection does not help either, because it counts as a serious defect.[4]
Not sure what is wrong with your car? Describe what you notice in the symptom diagnosis or see all fault codes.
Sources
Every fact on this page links to its source. If you find an error, let us know.
- P0506: Idle Air Control System RPM Lower Than ExpectedAutoDTCs · Technical documentation · consulted 31 October 2026
- P0506 OBD Error Code: Idle Air Control System RPM Lower Than ExpectedPartsAvatar · Technical documentation · consulted 31 October 2026
- OBD-Fehlercode P0506 (Leerlaufdrehzahl zu niedrig)CarWiki.de · Technical documentation · consulted 31 October 2026 · in German
- Desmontando mitos: ¿puede pasar mi coche la ITV con el testigo de «avería motor» encendido?Diariomotor · Motoring press · published 8 March 2021 · consulted 2 October 2026 · in Spanish