P0507 Code on a Buick: Idle Speed Higher Than Expected (Buick Guide)

P0507 on a Buick means the engine is idling faster than the computer asked for — GM's tables call it a high engine speed idle condition. On a modern Buick the computer controls idle with the electronic throttle, so a high idle almost always means air is getting into the engine that the throttle isn't controlling: a vacuum leak, a PCV fault, a loose oil cap or dipstick, or a throttle body that has learned the wrong idle setting. GM's documents for the Encore 1.4L turbo list P0507 among the codes caused by a leaking PCV orifice built into the camshaft cover — a part most owners have never heard of. And on the 3800 V6, GM treats a high idle seriously enough to make P0507 a first-trip code.

What Does P0507 Mean on a Buick?

At idle, the engine computer (ECM) picks a target speed based on coolant temperature, electrical load, A/C and transmission state. It then opens the throttle just enough to hold that speed. P0507 sets when the actual idle stays well above the target and the computer cannot bring it down.

Its mirror code, P0506, is idle speed lower than expected. For the GM-wide explanation of both, see our P0506/P0507 GM guide.

The key idea for diagnosis: if the throttle is already nearly closed and the engine is still idling high, extra air is entering somewhere after the throttle. That is why vacuum and crankcase leaks dominate the cause list, and why a new throttle body is rarely the first answer.

How GM's Monitor Decides

GM's OBD summary tables describe exactly when P0507 sets. Two Buick examples show the range:

Two practical takeaways:

• A slightly fast idle on a cold morning is normal. P0507 needs a sustained error of well over 100 rpm with the engine warm enough.
• On the 3800, GM's table says P0507 puts electronic-throttle vehicles into Limited Authority Mode, so a high idle there can come with reduced throttle response.

Encore 1.4L: The PCV and Crankcase Story

The 2013–2016 Encore with the 1.4L turbo (LUJ or LUV) has the clearest GM paper trail for P0507 on any Buick.

GM's preliminary information PIP5197D covers oil consumption, oil leaks, blue smoke, a check engine light or fuel trim codes. GM lists P0106, P0171, P0299, P0507, P1101 and P2096 as codes that may be current or in history. The recommended checks, in GM's order:

1. Dipstick and oil fill cap sealing — GM refers to PI0552. A cap or dipstick that doesn't seal is an unmetered air leak into the crankcase and intake.
2. Intake air leaks — GM refers to PIP4925.
3. The PCV orifice in the camshaft cover. GM notes the PCV orifice is an integral part of the camshaft cover. If its external port leaks oil or draws vacuum at idle, the camshaft cover assembly is replaced.
4. The intake manifold non-return valve. A missing valve can damage the PCV orifice diaphragm; if it is missing, GM replaces the intake manifold.
5. Crankcase pressure. GM gives normal readings of −11 to −18 inches of water at hot idle in park. Readings between −10 and 0 point to a cylinder leakage concern, which GM says is likely a weak or broken piston ring land.

A related GM document for the same engine, PI0907C (2013–2017 Encore), deals with P1101 but explains the mechanism behind a high idle neatly: a good throttle position at warm idle with accessories off is 8–12%. A reading below 7% means unmetered air is getting into the intake — the computer has nearly closed the throttle to compensate. GM's suspect there is the PCV pipe at the turbocharger inlet.

So on an Encore 1.4L with P0507, the order is cheap to expensive: oil cap and dipstick, intake and PCV leaks, the camshaft cover's PCV orifice, and only then crankcase pressure and the engine itself.

Throttle Body Idle Learn: The Step People Skip

Modern Buicks learn how much air the throttle body passes at idle and adjust for it as carbon builds up. That learned value can go wrong.

In bulletin 18-NA-171 for the 2016–2019 Encore 1.4L LE2, GM explains that "an un-metered air leak in the induction system, or an engine mechanical issue causing rough running, may cause the ECM to learn an incorrect Throttle Body Idle Airflow Compensation value over time," leading to symptoms including rough or unstable idle and stalling. GM's instruction after the repair is to inspect and clean the throttle body, then perform the Throttle Body Idle Air Flow Compensation Reset with GM's scan tool.

The lesson applies well beyond that one bulletin: after you fix a vacuum leak or clean a throttle body on any modern Buick, the idle can stay wrong until the learned value is reset or relearned. If P0507 returns right after a repair, ask whether the idle learn was done. Our throttle body cleaning guide covers the job itself.

3800 and 3.6L V6 Buicks

We did not find a GM bulletin that names P0507 on the 3800 or 3.6L V6 Buicks. The usual causes therefore come from GM's monitor logic rather than a documented pattern:

• Vacuum leaks — cracked hoses, a leaking intake gasket, brake booster hose or PCV hose.
• A dirty or sticking throttle that the ECM cannot close far enough, or an incorrect learned idle value after cleaning.
• EVAP purge valve stuck open. GM's 3800 table disables the P0507 test while a purge valve "stuck open" code is active, which tells you GM knows a stuck-open purge valve raises idle on its own. Diagnose any purge codes first.

Several V6 Buicks — 2008–2012 Enclave and LaCrosse, 2009–2011 Lucerne and 2010–2012 Regal among them — were covered by GM special coverage 14582 for a throttle position sensor fault causing rough running and reduced power. That coverage ran for 10 years or 120,000 miles from the in-service date, so for practical purposes it has passed; a dealer VIN check is still free. It is about reduced power, not P0507, but it is worth knowing if your Buick has both symptoms.

Symptoms of P0507

• Check engine light on — on a 3800, potentially after a single trip
• Idle noticeably higher than normal once warm
• Vehicle creeps harder at a stop; more brake pressure needed
• Harsher engagement shifting into drive or reverse
• A hiss from the engine bay (vacuum leak)
• On Encore 1.4L: oil consumption, oil on intake parts or fuel trim codes alongside
• On a 3800 with electronic throttle: limited throttle response

Causes and How to Confirm Each

How Is P0507 Diagnosed on a Buick?

1. Read all codes. Fix purge valve, throttle, MAP or MAF codes first — they change how the idle is controlled.
2. Check the basics: oil fill cap, dipstick seal, air intake duct clamps.
3. Compare actual and desired idle on a scan tool with the engine fully warm and accessories off.
4. Watch throttle position at idle. A very low reading with high rpm means extra air is getting in after the throttle.
5. Smoke-test the intake and inspect the PCV system. On an Encore 1.4L, follow PIP5197D for the camshaft cover PCV orifice and non-return valve.
6. Inspect and clean the throttle body if it is dirty.
7. Perform the idle airflow reset or relearn after any leak repair or cleaning.
8. Clear the code and verify at warm idle in park and drive.

Parts and Cost

Order throttle bodies and PCV parts by VIN — the same Buick model can use different engines and different parts.

GM Documents for P0507 on Buick Models

Have a dealer check your VIN against current bulletins rather than relying on any article, including this one.

What Other P0507 Pages Get Wrong

• "Replace the idle air control valve." Modern Buicks control idle through the electronic throttle body. There is no separate idle air control valve to replace on those engines.
• "Replace the throttle body." A high idle with a nearly closed throttle means extra air is getting in elsewhere. Find the leak first.
• Skipping the relearn. GM's own Encore bulletin calls for an idle airflow reset after repairs. Without it, the idle can stay wrong.
• Missing the PCV system. On the Encore 1.4L, GM's documented path runs through the camshaft cover's PCV orifice and the intake non-return valve.
• Ignoring purge codes. A stuck-open EVAP purge valve raises idle; GM's 3800 logic pauses the P0507 test when purge faults are present.

Frequently Asked Questions

Is P0507 serious?

It is rarely an emergency, but a high idle makes the car creep harder at stops and can mean an air leak that also upsets fuel trims. Fix it soon, and be extra careful with your foot on the brake when stopped.

My Encore has P0507 and uses oil. Are they related?

They can be. GM's PIP5197D lists P0507 along with oil consumption on 2013–2016 Encore 1.4L models and directs checks of the oil cap, dipstick, PCV orifice in the camshaft cover and crankcase pressure.

Why did P0507 appear after I cleaned the throttle body?

A clean throttle body flows more air than the computer's learned value expects. Perform the idle airflow reset or relearn with a capable scan tool, then let the engine idle fully warm.

Can a vacuum leak cause both P0507 and P0171?

Yes. Unmetered air raises idle speed and drives fuel trims lean. GM's Encore PIP5197D lists P0171 and P0507 together.

What's normal idle on a Buick?

It varies with engine, temperature and load. Compare actual idle with the desired idle on a scan tool rather than relying on a single number.

Does a high idle hurt the transmission?

Repeated harsh engagements into gear are not good for any transmission. That is another reason not to leave P0507 unfixed.