Prius 2001 Check Eng codes P0300 P0301 P0302P0303

Re: Prius 2001 Check Eng codes P0300 P0301 P0302 P0303

If your post is a request for help, then I suggest you do the following:

1. Remove the four spark igniters. Note that cylinder 1 is closest to the passenger-side of the car while cylinder 4 is closest to the inverter. Inspect each igniter carefully. If you see any faults in the plastic body such as cracks or rust stains, or if you see corrosion in the electrical terminals, replace the igniter in question.

2. Inspect the four wiring harness connectors that lead to the spark igniters and make sure there is no corrosion on the terminals.

3. Remove the four spark plugs and inspect carefully. If there is any rust deposit on the spark plug shell and the ceramic tail, replace the plugs. If the plugs are not the correct NGK or Denso iridium plugs, replace them with the correct plugs.

4. Remove the four wiring harness connectors that lead to the fuel injectors and inspect the connectors and the injector terminals for corrosion.

5. Remove and clean the mass air flow sensor using MAF sensor cleaner only. Also clean the throttle body interior and throttle plate using throttle body cleaner sprayed on a clean cloth or paper towel, then using the cloth/towel to scrub off the black gunk on the TB interior and throttle plate. Rotate the spring-loaded throttle shaft 90 degrees to clean the underside of the throttle plate.

6. Reinstall all removed parts. Make sure that the wiring harness connectors on the MAF sensor, spark igniters and fuel injectors are securely installed. You should hear a click sound when the lock on the connector is correctly engaged.

7. Drive the car and see if you still have intermittent engine misfire. If yes then check fuel line pressure which should be ~43 psi. If the fuel line pressure is not correct then remove and check the circuit opening relay to see if the relay has a problem. Measure resistance across the switched terminals when 12VDC power is applied to the relay coil, should be < 0.5 ohms. If the relay is good but fuel line pressure is low then the fuel tank (which contains the fuel pump) needs to be replaced.

8. If you can't find any other problems then the engine ECU may be at fault and need to be replaced.

 

It is a little far at 225 miles from you, but one of the best hybrid shops in the country is Taylor Automotive in Sanford, NC. If you need a shop to do the work for you, it is worth the extra cost to get your car up there. Further, if you did have a hybrid battery problem, they would be the ones to help you out anyway. Patrick gives great advice above, neatly summarizing the four requirements for engine start (air, fuel, spark, computer), but it presumes that you are already comfortable working under the hood on your car and have the equipment to do all of the testing.

 

I think Taylor Automotive is the closest non-dealer hybrid expert to you. They are definitely Gen I experts, having designed a replacement HV battery for the car. If you still have trouble, it sounds like it is at least feasible now to drive the car up there.

That said, gaining a marked improvement by cleaning the throttle plate suggests your problem is with the throttle/intake. Maybe take another look at the plate and see if there is any stickiness to its movement?

 

My only thought is that CC may not work if you have any current brake codes or trouble codes.

 

Wow, I am sorry to hear that. If the fan comes on during all this, then indeed the hv battery has a problem.

You said your Dad is a mechainc? If so, I am positive that he can help you rebuild it. You can go a long way with just replacing the one or two bad modules. Some folks have been able to get back on the road for as little as $30 bucks. Taylor Automotive also sells Gen I modules on ebay. Search here for rebuilding information.