986 Forum - The Community for Porsche Boxster & Cayman Owners - View Single Post - 99 Boxster Check engine light issue ( Not Normal)

JFP in PA · 05-18-2011, 12:24 PM

Both codes indicate that the current to the heated O2 sensors on both engine banks is not where it should be. These are typically not a sensor or relay issue, are most commonly a wiring issue; namely high resistance or an interruption of either the heater circuit or sensor wiring. Diagnostic tree in the OBD II manual is to test the sensor (always the first step), then start testing the wiring harness heading to the DME

This is why swapping parts did not fix it, there was probably nothing wrong with the original sensors. the final step in the diagnostic tree says it all, "Repair wiring harness."

05-18-2011, 12:24 PM	#10
JFP in PA Registered User Join Date: Feb 2005 Location: It's a kind of magic..... Posts: 6,608	Both codes indicate that the current to the heated O2 sensors on both engine banks is not where it should be. These are typically not a sensor or relay issue, are most commonly a wiring issue; namely high resistance or an interruption of either the heater circuit or sensor wiring. Diagnostic tree in the OBD II manual is to test the sensor (always the first step), then start testing the wiring harness heading to the DME This is why swapping parts did not fix it, there was probably nothing wrong with the original sensors. the final step in the diagnostic tree says it all, "Repair wiring harness." __________________ “Anything really new is invented only in one’s youth. Later, one becomes more experienced, more famous – and more stupid.” - Albert Einstein Last edited by JFP in PA; 05-18-2011 at 12:27 PM.