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Chevy Idle Air Control System RPM High
Specialized diagnostic report for Chevy owners dealing with the P0507 fault code.
Technician's Overview
🟡 SERVICE SOONPCM commanded idle RPM is lower than actual idle speed — engine idles faster than target. When this code is triggered in a Chevy, the engine control module (ECM) has detected an issue with the Idle Control system.
Common Symptoms
- High idle — 1,000–2,500 RPM at warm idle when in park in my Chevy
- Engine surges and hunts at idle in my Chevy
- Transmission clunk into Drive — higher than normal idle RPM at stop in my Chevy
Probable Causes
- Vacuum leak (most common) — cracked intake boot, disconnected vacuum line
- Dirty throttle body — carbon buildup preventing blade from seating
- IAC (idle air control) valve stuck open
- Throttle body actuator fault (electronic throttle — DBW vehicles)
Recommended Fixes for Chevy
- Inspect intake boot for cracks, especially near throttle body clamps
- Remove and clean throttle body with throttle body cleaner — do NOT use carburetor cleaner on MAF
- Perform throttle body relearn procedure after cleaning (many GM/Toyota models require it)
- Test IAC valve resistance (spec: 10–14 Ω typical); replace if out of spec
QUICK FIX TOOL
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Check PriceWhat P0507 is actually telling you
The engine is idling higher than the PCM asked for, usually by more than a couple of hundred rpm. The PCM controls idle by moving the throttle or the idle air control valve, and it can see that the engine is running faster than its target despite the correction. That means air is getting in through a path the PCM does not control, or the idle control device is not responding the way it should.
Can you keep driving? Drivable, but not pleasant. A high idle makes the car hard to slow down, can cause a lurch when you shift into gear, and hurts fuel economy. It will not damage anything on its own, so you have time to diagnose it. Do not start swapping the idle valve or the throttle body before you check for a vacuum leak, because that is the more common cause.
The usual suspects, in order
Each cause carries the one test that clears it or confirms it. Work down the list instead of buying parts.
- A vacuum leakAir entering after the throttle plate raises idle exactly the way an open throttle would, and the PCM cannot close a path it does not control. Intake gaskets, PCV hoses, brake booster lines, and cracked intake boots are the usual sources.How to check:Compare idle speed and fuel trims before and after pinching off suspect hoses, then smoke test the intake. A leak that only affects idle is a classic vacuum leak.
- A carboned-up idle air control valve or throttle bodyCarbon on the valve seat or around the throttle plate changes how much air bypasses at idle. On cable-throttle engines the IAC valve sticks; on drive-by-wire engines the plate does not seal the same way once it is dirty.How to check:Remove and inspect the valve or throttle body for black deposits. Command the idle control closed with a scan tool and see whether rpm drops as commanded.
- The idle relearn was never doneAfter cleaning a throttle body or disconnecting the battery, the PCM has to relearn the closed-throttle position. Until it does, idle sits high. This is extremely common right after DIY maintenance.How to check:Check whether the problem started right after a battery disconnect or throttle cleaning. If it did, run the relearn procedure before you replace anything.
- A leaking injector seal or an unmetered air path at the manifoldInjector O-rings that have hardened let air past the seal, which acts like a small vacuum leak that gets worse as the engine warms.How to check:Spray a small amount of carb cleaner around the injector bases with the engine idling and listen for a change in rpm. A change means a leaking seal.
- A load signal the PCM is reacting toA power steering pressure switch or an air conditioning request that never clears makes the PCM hold idle up on purpose, because it thinks a load is coming.How to check:Watch the load inputs in live data at idle. An input that is active when nothing is running is your answer.
Test it yourself, in this order
Do these before you spend anything on parts. The whole sequence takes about an hour of hands-on time.
1. Read target idle against actual idle5 min
Open live data at operating temperature and compare the commanded idle speed with the actual rpm, with all accessories off.
What good looks like:Actual within about 50 rpm of commanded. A large gap confirms the PCM is trying and failing to bring idle down, which points at uncontrolled air rather than a bad target.
2. Hunt the vacuum leak20 min
Pinch off suspect vacuum hoses one at a time while watching idle speed, then smoke test the intake if nothing obvious shows.
What good looks like:Idle drops when you pinch the leaking line. Smoke escaping anywhere between the throttle body and the head confirms the leak location.
3. Command the idle control and watch the response10 min
With a scan tool, command the IAC or electronic throttle to reduce idle, in steps, and watch rpm follow.
What good looks like:Rpm falls as commanded. No response means the valve or the throttle actuator is not doing its job, or the passage to it is blocked.
4. Run the idle relearn if the timing fits20 min
If the problem started after a battery disconnect or throttle cleaning, run the manufacturer's relearn procedure.
What good looks like:Idle settles back to spec within the relearn window, which is usually a few minutes of idling plus a drive cycle.
What this costs for Chevy owners
Doing it yourself: Throttle body cleaner $10-$15 plus a gasket. IAC valve $40-$150. Vacuum hose $10-$40. Intake gasket set $30-$120 if the leak is at the manifold.
Paying a shop: Diagnosis with a smoke test $80-$150. Idle valve or throttle body service $150-$400. Intake gasket replacement $400-$900 depending on access.
The two cheapest fixes here are also the two most common: cleaning the throttle body properly and running the relearn, and finding a split vacuum hose. Both cost almost nothing and both get skipped in favour of a new valve.
The tool this diagnosis needs
You need bidirectional control so you can command the idle control device and watch the engine respond, and you need the ability to run an idle relearn on drive-by-wire cars. That relearn is the reason a lot of DIY idle repairs never finish: the part is right and the car still idles high because the PCM was never told to relearn.
See which scanners stream live dataChevy-specific notes
On drive-by-wire 4.3, 5.3, and 6.0 engines, a dirty throttle body is the usual cause and the relearn is mandatory afterwards. On older cable-throttle engines, check the IAC valve and look for a split vacuum line at the back of the intake.
When to stop and pay a shop
Stop if the relearn procedure requires a factory-level tool your scanner cannot run, if the idle problem started after someone else cleaned the throttle body and the car now needs a dealer relearn, or if the leak is under the intake manifold on a V engine.