Mooney 20 pilot reported a carbon monoxide alert and becoming lightheaded led to a diversion.

Attributes
ACN	1592265
Time
Date	201811
Environment
Flight Conditions	Mixed
Light	Daylight
Aircraft 1
Make Model Name	M-20 E Super 21
Operating Under FAR Part	Part 91
Flight Phase	Cruise
Route In Use	Direct
Flight Plan	IFR
Person 1
Function	Single Pilot
Qualification	Flight Crew Flight Instructor Flight Crew Air Transport Pilot (ATP) Flight Crew Instrument Flight Crew Multiengine
Experience	Flight Crew Last 90 Days 30 Flight Crew Total 3500 Flight Crew Type 160
Events
Anomaly	Aircraft Equipment Problem Critical Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor Flight Deck / Cabin / Aircraft Event Illness

Narrative:

I had a carbon monoxide alert in the cockpit. Initially I descended to 6000 feet and opened the vents. Then got light headed and [notified] center. Then I got vectors to my divert airport and opened the door and side window for ventilation. I got really light headed with the carbon monoxide but was able to fly an ILS and land.

Original NASA ASRS Text

Title: Mooney 20 pilot reported a carbon monoxide alert and becoming lightheaded led to a diversion.

Narrative: I had a Carbon Monoxide alert in the cockpit. Initially I descended to 6000 feet and opened the vents. Then got light headed and [notified] Center. Then I got vectors to my divert airport and opened the door and side window for ventilation. I got really light headed with the Carbon Monoxide but was able to fly an ILS and land.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.