When you have an idle engine, the RPM must be managed to accommodate the other loads put on the engine. Some of the most common loads include the windshield wipers, heater, air conditioner, integrated GPS system, and radio. The more devices and systems that are activated, the more stress the idle engine is put under. That is why an idle air control system is used to manage the load and stress put on the engine.
Without a functional idle air control system, the engine speed will increase drastically as the load increases on the engine. This could end up overheating and damaging the engine if it is not fixed. You’ll know when this problem occurs by looking at the tachometer on the dashboard. If the needle is going above 2,000 RPM or behaving erratically while the engine is idle, then you likely have a problem with the idle air control system.
It is important for the engine idle speed to remain consistent. In normal circumstances, the RPM of the idle engine remains the same. There is a predetermined level set forth by the manufacturer of your car. Look in the owner’s manual to find out the exact level amount. Once the needle goes above that level for more than 10 or 20 seconds, then you know there is a problem.
Run a diagnostic check on the powertrain control module if you experience this symptom. The screen on the scanning tool will likely display trouble code P0507. This verifies that the idle air control system RPM is higher than expected. Since the idle air control system is in constant communication with the powertrain control module, any erratic behavior coming from the idle air control system will prompt the module to warn you about it.
- P0325: Knock Sensor 1 Circuit Malfunction
- P0121: Throttle Position Sensor/Switch A Circuit Range/Performance Problem
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Aside from the higher engine idle speed, other symptoms you may experience are a rough idling engine and the Check Engine warning light turning on. There are several components of the idle control system which could have caused this problem. You might have a bad idle air control motor, coolant temperature sensor, alternator, power steering pressure switch, or a leaky intake manifold vacuum. Sometimes the air passages in the throttle body have carbon accumulation too. All of these areas are worth exploring.