Toyota Repair Problems? Ask a Mechanic for Answers ASAP
Is the vehicle currently running right now or will it start up and run? Do you have the specific code number Set in the computer?
That is fine I'll still be here get the code numbers and post them back as you have been replying to me do not open another question.
How many miles on the car?
First an explanation of these codes. The P0 300 code through P0 306 are misfire codes. This is probably a result of the P0 171 and P0 174 codes which means the engine is running lean on both banks. 90% of the time this is caused by either an intake leak in the induction boot or a vacuum hose being off or the most common problem is the mass airflow sensor being contaminated. Remove the mass airflow sensor from the induction boot/air cleaner assembly and look down into the extension housing there are two tiny resistors in there that should be clean and shiny what you'll find is they are contaminated with dirt and grit. Clean those little resistor wires with brake cleaner or mass airflow sensor cleaner than reinstall. Remove the negative battery cable for about five minutes to erase the codes and reset the learned value in the computer. This should resolve the lean condition problem. The P0420 code means that bank one catalytic converter is below the threshold required to meet federal admissions standards. This usually means the converter is failing but before you get into that problem deal with the lean problem. It's possible blinking that it could be setting a false P0420 code. Please do not forget to rate the assistance that I provided you at three or higher and if you need additional assistance feel free to reply and I will get back to you. It's not likely that the injectors are the issue they very rarely fail on this engine.
That would be the first thing to start with removing the negative battery cable to clear the codes. Then see what codes come back first make sure they repaired all of the intake leaks. the mass airflow sensor is mounted in the intake air boot housing. If you're not familiar with that I probably wouldn't mess with it.