P0507 and your Nevada smog check

A high idle is one of the codes drivers can sometimes hear: the engine revs a little higher than usual at a stop light, or the car creeps more than it used to. Whether you notice it or not, the computer does, and once it sets P0507 the check engine light decides your Reno smog check result.

At a glance

• SAE J2012 definition: Idle air control system RPM higher than expected.
• Unmetered air getting into the engine is a frequent reason an idle runs high.
• Nevada fails 1996 and newer light-duty vehicles with the check engine light on (DMV).
• Repairs before the first failed test do not count toward a waiver.

Print this checklist

1. Leave the code stored

   Clearing it brings a not ready rejection.

2. Bring the renewal notice

   Ask about renewing your registration in the same visit if the car passes.

3. Keep every receipt

   Washoe waiver receipts must be tied to the failure on the initial test.

Target idle versus actual idle

When you take your foot off the pedal, the engine computer picks a target idle speed based on things like engine temperature and whether the air conditioning is on. It then controls the air entering the engine at idle to hit that target, using an idle air control valve on older designs or the electronic throttle on newer ones.

SAE J2012 names P0507 "Idle air control system RPM higher than expected." The computer stores it when the actual idle stays above its target and the system cannot bring it down. In other words, more air is reaching the engine than the computer planned for, or the control itself is not responding.

Signs some drivers notice

• Idle speed that sits higher than normal once the engine is warm.
• More creep at a stop when the car is in gear.
• An idle that hunts up and down.
• Or nothing at all except the lamp.

Common causes a repair shop checks

Common causes a repair shop checks for a high-idle code include a vacuum leak from a cracked hose or intake gasket, a dirty or sticking throttle body or idle air control valve, a leak in the intake tube after the air flow sensor, and a throttle that needs its idle relearned after other work. A repair shop decides which applies and how to correct it.

The rule at a Nevada OBD test

A Nevada smog check on a 1996 or newer car or light truck is an OBD II inspection. The technician scans the VIN, connects to the port under the dash, and the analyzer reads the computer. P0507 lights the lamp, and a lit lamp is a fail regardless of how the idle sounds that day.

Why test before the repair

The DMV's advice is to get tested even with the light on. A failed test is a legal document showing why the vehicle fails. If your registration has already expired, it allows a ten-day movement permit at reduced cost so the car can be driven for repairs. It entitles you to a challenge test at the emissions lab. And it is the starting point of the waiver process, since money spent on repairs before that first failed test cannot be counted.

There is one shortcut to avoid. Clearing the code with a scanner or disconnecting the battery to turn the light off makes the car come back rejected as not ready, the DMV says, and then it needs up to a week of varied driving before it can be tested.

After the repair

Once the idle problem is fixed and the codes are cleared, drive the car through a normal week of city and highway trips before the retest. If it still fails after repairs, the Washoe waiver requires receipts of at least $200 in parts and labor at a 2G licensed authorized station for repairs directly related to the failure, or at least $200 in related parts the owner bought within 14 days after the initial test. Our repair and retest page lays out the order.

If the vehicle is newer, ask the dealer about a recall or the federal emissions warranty before paying. Federal law covers some expensive emission components for up to 8 years or 80,000 miles.