2007 Prius w 120k miles Error code p0302

Hi folks: My check engine light came on and I knew I needed a muffler replacement so I had my mechanic take a look and he says I'm getting p0302 and that the recommended remedy is "Engine replacement" but that we could replace the spark plugs and hope that we beat the statistics. I was hoping to run this car to the ground. Toyota replaced the hybrid battery about 6 months ago. I told them to go ahead and replace the spark plugs because I haven't replaced those at all yet. Is engine replacement an exaggeration? He said he only had one customer where they paid to do some work but in the end, the engine still needed replacing. I thought toyota engines were supposed to last a very long time, I'm not ready for another car yet and thought I was buying myself a couple more years with the new battery. But I can't see spending several thousand on a new engine. My partner suggested not spending the $600 on the exhaust work until we see if the spark plugs fix the problem, however the muffler is currently not attached to the exhaust pipe and I have no other car and I need to get back on the road. Any advice is deeply appreciated.

 

I haven't seen any dripping or stains under the car. They have already replaced the spark plugs and say the car has not misfired since. MPG is averaging around 42 but I living in a pretty hilly area. The times I've done highway driving since replacing the battery it was getting closer to 50 but I haven't done that kind of driving since I noticed more noise out of the back end.

 

Mechanic has also reported that there doesn't seem to be evidence of any head gasket leak or issue. They are not encouraging engine replacement, just to be clear.

 

It's just louder engine noise. The muffler was visibly detatched from the exhaust pipe before I brought it in. I live in a high salt area. I do have a kid and dogs.

 

As soon as I told him I was going to run the code by my good friends at PriusChat he was a lot straighter with me. I appreciated the fact that he gave me an opportunity to decline the exhaust work even though the spark-plug replacement seemed to resolve the issue. I'm planning to get a new car in 2020 (Prius Prime? CrossTrek plug in? not sure yet) but I want to keep this car as a backup as long as possible and right now it's my only vehicle.

 

No they are working on it now. The muffler was completely rusted. They are replacing it and the pipe but not the part of the pipe that includes the catalytic converter.

 

For now hopefully. I guess all the maintenance I was able to avoid prior to 100k is catching up with me now. This year I've done the hybrid battery, serviced all the fluids, replaced a wheel bearing (I live in pothole city), now the spark plugs and exhaust. Wish I knew what to expect next or felt secure driving this car a few hundred miles to visit my mother. Time to plan for my next vehicle. Maybe a prius Prime next I don't know.