GMC-specific code — factory diagnostic data| DTC Data Sheet | |
| Code | P0506 |
| Vehicle | GMC Sierra 1500 (2007-2019) |
| Engine | All |
| System | IDLE CONTROL |
| Fault type | Performance |
| Official meaning | Idle Air Control System RPM Lower Than Expected |
Definition source: GMC factory description. Diagnostic guidance is based on factory-defined fault logic for this code.
Decode any GMC Sierra 1500 VIN — free recalls, specs & safety ratings — free VIN decoder with NHTSA data
Looking for the cross-vehicle definition? Read the generic P0506 article for the SAE-defined fault logic that applies to all manufacturers.
P0506 Quick Answer
P0506 on a Sierra means idle RPM dropped below the PCM’s commanded idle. On the Gen-IV LS family with electronic throttle, this is almost always carbon buildup behind the throttle plate restricting airflow at idle. Less common: vacuum leak, stuck PCV, or failed throttle actuator. A $10 throttle body cleaning resolves ~70% of cases.
What Does P0506 Mean on a GMC Sierra 1500?
The GMC Sierra 1500 (2007-2019) shares the GMT900 / K2XX chassis and Gen-IV LS engine families with the Chevy Silverado 1500. P0506 root causes match the Silverado pattern exactly. The model-specific failure modes documented below apply to all Sierra trim levels using the same engine.
Symptoms
- Rough or low idle, occasional stalling
- Check Engine Light (P0506)
- Hesitation at tip-in
- Increased fuel consumption
Common Causes (Most Likely on This Model First)
- Carbon buildup behind throttle plate. Sierras > 60k miles. Clean with CRC Throttle Body cleaner — never carb cleaner (eats the coating).
- Throttle body relearn required after cleaning or battery disconnect. Without relearn, idle position is wrong.
- Vacuum leak. PCV hose, brake booster, or intake gasket. Often paired with P0171/P0174.
- Faulty electronic throttle actuator. Dead spots in the motor. Bidirectional command + watch response.
- Sticky AFM lifters. AFM transition gets stuck in a half-state and idle compensates wrong.
Diagnostic Approach
- Inspect back of throttle plate. Visible carbon = clean it.
- Clean with CRC Throttle Body cleaner.
- Perform throttle body relearn or drive 5-10 ignition cycles.
- Smoke-test for vacuum leaks if cleaning doesn’t resolve.
- Bidirectional throttle command — watch actual position track smoothly.
Possible Fixes
| Fix | When |
|---|---|
| Throttle body cleaning | Carbon visible — fixes ~70% |
| Throttle relearn | After cleaning |
| Vacuum leak repair | Smoke test reveals leak |
| Electronic throttle body replacement | Dead spots in actuator |
Can I Still Drive With P0506?
Short-term yes but stalling at stops is a real risk. Address before it escalates.
How Serious Is This Code?
Low to moderate. The fix is usually a $10 can of cleaner.
Repair Costs
| Repair | Cost |
|---|---|
| Throttle body cleaning (DIY) | $10 |
| Cleaning (shop) | $80 – $180 |
| Electronic throttle body | $340 – $720 |
FAQ
How do I fix P0506 on a GMC Sierra?
Start with throttle body cleaning — 70% of Sierra P0506s are carbon buildup. Use CRC Throttle Body cleaner ($10, 30 minutes). Then perform throttle relearn or drive a few ignition cycles.
Why does the Sierra throttle body get dirty?
Crankcase blow-by from the PCV system carries oil mist into the intake. It deposits on cool surfaces — the throttle plate is one of the first stops. AFM trucks are especially prone because oil consumption is higher.
Can I drive my Sierra with P0506?
Short-term yes — but expect rough idle and possible stalls at stops. Address before stalling in traffic becomes a real issue.
Will throttle cleaning fix P0506 on my Sierra?
Most of the time, yes. After cleaning, the throttle body needs to relearn its idle position — either via a scan tool command or by driving 5-10 ignition cycles.