can a defective head gasket cause a cylinder to run lean and miss with out showing any other signs of a leak
Aug 7, 2009 at 4:28 AM
FACTORYJACK
✓Experienced Mechanic
4,159 POSTS
It can definately cause it to miss, as the coolant doesn't burn. It would create more unburned fuel in the system, that may cause it to indicate rich. The coolant is also capable of contaminating the O2 sensor.