Questions and Answers

Jeep Grand Cherokee DTC 43 Q. Vince, You have helped me with past problems with my 1997 Jeep Grand Cherokee Laredo. This is the 5.2 liter V-8 engine. I have 147,300 miles on it and tuned it up, plugs, wires and distributor cap, about 20,000 miles ago. I have a new problem now. My Check Engine Light (CEL) came on and the fault code is 43 which is, if I am correct, a misfire in cylinder #1. So what I gave done was the following but nothing has worked...

1. Thinking I had a fouled spark plug, I replaced the spark plug on cylinder one.
2. Checked the resistance level in all the ignition wires using a multimeter.
3. Used a wire tester as a second test to make sure the wires were good.
4. Performed a compression test with Cylinder #1 at 130 psi and Cylinder #3 at 145 psi.
5. Have been watching my engine oil level to determine if it is burning excessive oil. Will know better in a couple of days.

At this point I have run out of what else to check to determine the problem. I know that my Catalytic Converter is bad. I also replaced the upstream or forward Oxygen Sensor that is before the CC last year. I didn't think a bad Catalytic Converter would cause a 43 fault code though.

Any help would be greatly appreciated...
Thanks,
TB

A. DTC 43 indicates a cylinder misfire, but does not specify which cylinder is misfiring. To pinpoint which cylinder is misfiring, you need a scan tool and get the "P" code, as you can see in the chart below. So it is quite possible you're barking up the wrong tree.

If you go to an Autozone they will scan the codes for you, if the CEL is currently on, and tell you the DTCs they find. That will get you closer to the problem.

I'm fairly confident that if you do a complete tune-up, spark plugs, spark plug wires, distributor cap and rotor, that the misfire codes will be taken care of. Be sure you read this, Dodge Ram 1500 Running Rough before replacing the spark plug wires, or if you have already replaced them.