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2000 Sonata downshifts and dies after 10 minutes of driving

03-22-2008, 10:12 PM
Need advice please! The car is a 2000 Sonata 2.4, auto. After driving about 10 minutes or so, the car will downshift,(if at freeway speeds) and die. The check engine light comes on at this time also. Ck'd computer;codes were p0335, p0760, p0755, p715, and p725. went to Hyundai site and their troubleshooting flow chart led me to think that the engine computer might be bad. Replaced the computer, (with a computer w/same part number),car started and drove fine, but did the same thing about four or five miles down the road. It seemed like it shifted a little differently, but ran great while it ran. Now the codes are p0335, and p0725.
Appreciate any help! I had already replaced both coil packs previously to this latest problem. dont know what to try next, and I really need this car to run. Thanks.

03-24-2008, 04:29 AM
I would bet your crankshaft position sensor is grounding out. When they go "bad", they ground out, bad design. I had mine changed 5k ago and this one too went to ground. The routing of the wires goes around a sharp curve that cuts through the protective cover then through the wires themselves. I'm in the process of putting a new one end and trying to get my money back from shop that did the repair before. I bet yours is vibrating a bit and is just barely touching the engine block giving you all those problems. 99% sure of it.

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