Originally Posted by
tancookbelle
Revised - Second coil failure occurred due to heat. Thermostat failed. See end for more detail
FYI. Recently had an ignition coil failure that cause engine to stop and car needed to be towed home. There was some indication over the previous six months of a possible problem when the engine seemed to lag/pause/miss briefly when accelerating between 2nd and 4th gears. The engine worked fine when driving 60 to 120 kph. No check engine light however when I checked codes I would sometimes get "P030600 Misfire on #6 cylinder".
Once car towed home I checked for codes and got "P035100, P035200, P035300, P035400, P035500, P035600, Ignition Coil "A" Circuit Primary/Secondary Malfunction" and "P030600 Misfire on #6 cylinder". I looked at electrical diagram for Engine Control Module (ECM) and identified fuse 35 as providing power to the coil circuit. Checked fuse 35 and it had blown. Installed new fuse and car started but immediately stopped. Checked fuse 35 and it had blown again which meant problem was in coil circuit. I decide to disconnect plug from coil #6 which had showed code P030600. This coil is on right side of engine when looking towards car. Installed new fuse, started car and it ran on five cylinders.
Installed new coil (part 30684245) and car is operational once again. In future if a get a Code P0301000 to P030600 I will change the coil immediately even if there are no obvious signs of misfire.
Post repair note: Another coil failed and it is now clear that engine high temperatures caused this failure. This high temperature caused the ECM safety system to cut back coils until the engine stopped. Once stopped the high temperature residual heat cause #2 coil to also fail. Interesting the only warning I received was a graphic in the right message display of a thermometer in water and a message saying to up shift. There was no high temperature statement. Waiting for both new coil and new thermostat kit
Car repaired now. The thermostat failed causing engine to over heat enough to fail ignition coils. One of two plastic tabs within the thermostat failed causing the thermostat and re-circulation valve to come loose. See photo for details. Took about 2 hours to take inlet manifold off, remove thermostat, and 1-1/2 hours to reinstall. Also changed alternator coupling which took 1/2 hour. Test car on 100 km trip and everything is fine. Temperature cycle from 88 C to 92 C and eventually settled at 90 C.
In summary a coil failure combine with the information display showing a thermometer & shift up warning probably indicates a thermostat failure.
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