Trouble Code P0505 on your Nissan Maxima indicates an Idle Air Control System malfunction, which may be caused due to either an unplugged or defective Idle Air Control Valve (IACV). Typically when the IACV fails on this vehicle, it almost always damages the ECU (Engine Control Module). If this is the case, after replacing the IACV you will need a new ECU as well. The ECU will need to be programmed and the Idle Air Control System re-learned.
Replacing the IACV will be your first task. After which you will need to erase the P05050 OBD II trouble code using a scan tool (in order to turn off the check engine light). Next the Idle Air Control Valve will need to re-learn it's position and reset itself. If code P05050 re-appears after this is all done, then chances are the defective IACV damaged the ECU, and the ECU will need to be replaced.
If you will be replacing the IACV yourself, the following is the IACV learning procedure:
Turn ignition switch “ON” and wait at least 1 second.
2. Turn ignition switch “OFF” and wait at least 10 seconds.
3. Start engine and warm it up to normal operating temperature.
4. Check that all items listed under the topic “PRE-CONDITIONING”
(previously mentioned) are in good order.
5. Turn ignition switch “OFF” and wait at least 10 seconds.
6. Start the engine and let it idle for at least 30 seconds.
7. Disconnect throttle position sensor harness connector (brown),
then reconnect it within 5 seconds.
8. Wait 20 seconds.
9. Make sure that idle speed is within specifications. If not, the
result will be incomplete. In this case, find the cause of the
problem by referring to the NOTE below.
10. Rev up the engine two or three times. Make sure that idle
speed and ignition timing are within specifications.
The Idle Speed you are trying to achieve is below:
Idle speed M/T: 625±50 rpm
A/T: 700±50 rpm (in “P” or “N” position)
Ignition timing M/T: 15°±5° BTDC
A/T: 15°±5° BTDC (in “P” or “N” position)
posted by SmogTips Support
