P0506 on GMC: How to Diagnose & Fix
Idle Air Control System RPM Lower Than Expected
1 GMC model · 1 documented issue · 1 critical
P0506 on GMC by model: symptoms, diagnosis and fix
On 1.5L LYX-equipped Terrains the charge air cooler outlet tube can separate from the throttle body inlet. The retaining clip design does not hold the duct under boost pressure and heat cycling, so the tube pops off, dumping boost and unmetered air. GM issued Service Update N192266090 covering the charge air cooler duct disconnect at the throttle body on 2019 Malibu, Equinox and Terrain 1.5L vehicles, and the condition is further covered by field bulletins PIP5651 and 22-NA-224 across the 2018-2022 range. This is separate from the frozen-CAC condition: the cooler is fine, the connection has come apart. It is also distinct from the throttle body / TPS electrical failure already documented, because the fault is mechanical air-path separation.
Common Symptoms
- Sudden loss of power while driving
- Reduced engine power message
- Check engine light
- Loud whoosh or rushing air sound from engine bay
- Rough idle or stall at low speed
How to Fix
Inspect the outlet duct and throttle-body connection, reseat the duct and install the improved retainer when the duct and sealing surfaces remain serviceable. Replace a damaged duct rather than relying on the clip alone, and use the free service update when the VIN qualifies.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Genuine GM 84828210 charge-air-cooler retainer (supersedes 13434668)$4
2018-2022 GMC Terrain 1.5L turbo branch covered by the service procedure. The OEM catalog also lists the 1.6L diesel, but this issue record is the LYX 1.5L; inspect the duct before ordering.
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Sources for this issue (3)
P0506 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P0506 mean on a GMC?
P0506 stands for "Idle Air Control System RPM Lower Than Expected." This code means the engine computer detected that the engine's idle speed is lower than the target idle RPM it commanded. The PCM controls idle speed through the idle air control valve or electronic throttle and sets this code when the actual idle drops below expected. A low or rough idle can cause stalling, hesitation, and reduced drivability. On GMC it is documented across 1 model: Terrain.
What are the most common causes of P0506?
The most common causes of P0506 are: Vacuum leak in intake or hoses, Dirty or carbon-clogged throttle body, Faulty idle air control (IAC) valve, Dirty or failing mass airflow sensor, Clogged PCV system or EGR sticking open, Worn or dirty fuel injectors, Excessive engine load from accessories. The specific cause varies by vehicle.
How much does it cost to fix P0506 on a GMC?
Repair costs vary widely with the root cause and GMC model; each issue on this page carries its own estimate where one is published.
Looking for P0506 on a different make?
View P0506 across all makes →Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.