PO301... Misfire in Cylinder 1

If the car is driving OK other than the misfire I think you should be able to drive it home and let your mechanic look at it. You need to be prepared for the worst on the drive home though.

 

It might help to know your year and mileage. Could be a one time issue or a problem that will happen again. If the engine is running smoothly, might be OK. IF it becomes rough, I would not drive it. A flashing check engine light (right now it is on steady?) means you should stop ASAP. Can you extend your visit by a day and have someone look at it before you hit the road? Good luck, and let us know how it turns out.

 

DTC P0301 means that cylinder 1 has a misfire. This is the cylinder closest to the passenger-side fender.

1. How many miles on the odometer?
2. When were the iridium spark plugs last replaced?
3. What drivability symptoms do you notice? Is it obvious the engine is misfiring?
4. Check the wiring harness connectors to the spark igniter and the fuel injector for cylinder 1.

If you do not notice a problem with #3 above then you can return home. If it is obvious the engine is having problems, then get the car fixed before you embark on a long road trip.

The cost to fix depends upon what is wrong. Plan on $200 - $300.

 

3. I think you should drive around and see how bad the misfire is.
4. Hmmm - Toyota service - plan on $500.

Any competent mechanic should be able to determine the cause of an engine misfire. The key is whether or not the mechanic in question is actually "competent".

Further, a mechanic who does not have experience with Toyota hybrids probably won't understand the concept of inspection mode, which is used to keep the engine running continuously. Then the mechanic will waste time just trying to understand why the engine does not run when not under load.

 

What type of gas do you use? Have you used any gas additives / fuel injector cleaner recently? Any symptoms prior to the code appearing?

 

If you can swap the coil in cylinder #1 to #2, reset the DTC, and if a new code comes up and shows that the misfire is in cyl 2 now, the coil itself needs to be replaced. If the code shows the same cyl 1 misfire, you may have a premature fouled sparkplug.

Other problems that are possible but not likely could be fuel injector or head gasket.

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It's possible that it could have been a fluke. Not much a shop can do without a DTC or symptoms.

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Did it recently rain? Maybe a slight amount of moisture got into the cylinder 1 spark plug tube which caused the misfire - and the moisture dissipated.

If you don't notice any drivability issues and the check engine light is off, you can reasonably embark on your return trip home without having the car serviced.

 

Almost sounds like a loose electrical connection IMO( no problem before, and problem went away). Might be a good idea to pop the hood and look around cylinder #1 to see if all connections are tight. Any recent maintenance or any damage under the hood? When did you fill up at Costco and what is the fuel level? Where was the gas prior to the costco fill up and what was the level then?

 

Mechanic here, don't drive on a misfire. Replace the spark plugs. My prius needed plugs at 60,000 120,000 and 180,000 miles. It's easy to do yourself with a few hand tools. But should run you about $200 at a shop. If the plugs don't fix it you will need a coil for the #1 cylinder. That's on the far left. Roughly $90 without labor. Let me also say that I once did drive a prius for a few days with a minor misfire and burned the catalytic converter. That was EXPENSIVE.

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If it was a Gen2 I say check the plug for tightness and pull one to see condition. Gen3 I believe it's less easy to get to the plugs. The Gen3 had the issue sometimes if you did a really short drive cold, like backing out the garage to park onto the street, and then turn off engine, there could be knocking upon restart.

 

It's just a plastic cover that you need to pull up on to access the coils

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@ 60k - cabin filter, engine air filter, oil change and rotate tires. @65k oil change and rotate tires with brake inspection. Really these cars done need much. Expect to do a water pump at around 160k. Tires and front brakes when worn. That's all a prius really needs. I did a CVT fluid exchange @ 180k for my own peace of mind. Had minor electrical issues with nav but nothing ever crazy. I work on BMWs and drive a Toyota for a damn good reason. Peace of mind and zero maintenance cost... Essentially.

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