What P0506 means
The computer is holding idle as high as its control authority allows and the engine still idles below target. Something is dragging the idle down — restricted airflow through a dirty throttle body, or a load the computer didn't budget for.
What you’ll notice
- Low, lumpy idle — tach below its usual mark
- Stalling risk when accessories load up
- Sometimes vibration at stops (engine lugging at low RPM)
Likely causes and repair cost
Broad US independent-shop bands, parts and labour.
Can you drive with P0506?
Yes — this is the gentler sibling of P0505, usually announcing a throttle body due for cleaning before it graduates to stalling.
The misdiagnosis to avoid
Ignoring it until it becomes P0505-with-stalling. This code is the early, cheap window: a $100 cleaning now versus the same cleaning later plus the stall-at-intersection stories. Low-idle codes reward promptness disproportionately.
Describe what it’s doing in your own words and the symptom checker gives you a safe-to-drive verdict, ranked causes with costs, and notes to take to the shop — free, no sign-up.
Read the code yourself
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Check price on AmazonQuestions people ask
How does carbon lower my idle?
Idle air flows through precisely-sized passages around or through the throttle plate; carbon buildup physically narrows them. The computer opens its idle control further to compensate until it runs out of range — then idle sags below target and this code sets. The carbon accumulated over years; the code marks the day compensation ran out.
Is low idle bad for the engine?
Mildly and cumulatively — an engine lugging below its designed idle vibrates more, charges less, and stalls easier, and the transmission engages harshly from it. Nothing dramatic; just an engine running outside its comfortable spot until a straightforward cleaning restores it.