Engine-Codes - Mercedes-Benz - P0505 Mercedes-Benz

P0505 Mercedes-Benz Code - Idle Control System Malfunction

- Code Popularity: 18,518 Views
- Repair Importance Level: 3/3
- Repair Difficulty Level: 2/3
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What are the Possible Causes of the DTC P0505 Mercedes-Benz?

NOTE: The causes shown may not be a complete list of all potential problems, and it is possible that there may be other causes.
  • Faulty IACV-AAC valve
  • IACV-AAC valve harness is open or shorted
  • IACV-AAC valve circuit poor electrical connection
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How to Fix the DTC P0505 Mercedes-Benz?

Check the 'Possible Causes' listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector pins.

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What is the Cost to Diagnose the Code?

Labor: 1.0

The cost to diagnose the P0505 Mercedes-Benz code is 1.0 hour of labor. The diagnosis time and labor rates at auto repair shops vary depending on the location, make and model of the vehicle, and even the engine type. Most auto repair shops charge between $75 and $150 per hour.

When is the Code Detected?

The P0505 code is set when the IACV-AAC valve does not operate properly.

What are Code Possible Symptoms?

  • Engine Light ON (or Service Engine Soon Warning Light)
  • Engine hard to start
  • Rough or erratic idle speed

What Does the P0505 Mercedes-Benz Code Mean?

This system automatically controls engine idle speed to a specified level. Idle speed is controlled through fine adjustment of the amount of air which by-passes the throttle valve via Idle Air Control Valve IACV) and Auxiliary Air Control AAC) Valve. The IACV-AAC valve changes the opening of the air by-pass passage to control the amount of auxiliary air. This valve is actuated by a step motor built into the valve, which moves the valve in the axial direction in steps corresponding to the Engine Control Module (ECM) output signals.
One step of IACV-AAC valve movement causes the respective opening of the air by-pass passage. (i.e. when the step advances, the opening is enlarged.) The opening of the valve is varied to allow for optimum control of the engine idling speed. The crankshaft position sensor (POS) detects the actual engine speed and sends a signal to the ECM. The ECM then controls the step position of the IACV-AAC valve so that engine speed coincides with the target value memorized in ECM. The target engine speed is the lowest speed at which the engine can operate steadily. The optimum value stored in the ECM is determined by takig into consideration various engine conditions, such as during warm up, deceleration, and engine load (air conditioner, power steering and cooling fan operation).

P0505 Mercedes-Benz Code - Idle Control System Malfunction

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