I pulled the CEL code and code reader spits out P0303 cylinder 3 misfire. History : At 160k I changed the spark plugs with OEM toyota plug. 2009 Prius 180k Drive really rough and check engine light is on. Clear code and pulled off #3 ignition coil and switch it with #2 coil. Ran car around the block and noticed ODBII reader and another check engine light P0303 again. Car still running rough and checked the forum and found out could be #3 injectors. Going to buy a set of new injectors but wanted the forum's opinion could this be the problem? SM-J737T1 ?
Where did you buy the plugs from and what brand are they? There have been reports of fake NGK plugs being sold on E-Bay.
If you swapped the plug and coil, and the problem didn't follow, then that could be a next step. I picked up four (4) reconditioned for under $30 including shipping, they seemed to work and the fuel trims fell back in line. Here is the workup for DTC P0303 : https://share.qclt.com/%E4%B8%B0%E7%94%B0%E6%99%AE%E7%91%9E%E6%96%AF%E5%8E%9F%E5%8E%82%E8%8B%B1%E6%96%87%E6%89%8B%E5%86%8Cpdf%E6%A0%BC%E5%BC%8F/Repair%20Manual/04pruisr/05/2054m/cip0300.pdf Also check from carbon tracking on the COPS.
I fixed the problem by troubling shooting all the possible out comes. I swapped the coils drove around the block and got P0303 error code. I swapped Injectors and drove around the block and P0303 error code again. I read long ago that ebay has sellers who sold fake NGK plugs and decided to pull the plugs out. Even though I only drove 20,000 miles on them. Yup the plugs gaps we're way out of spec. 1.4mm. Man I was pissed off. I keep my old plugs and clean them up. Put the old one back in and now I have 4 fake plugs. People beware of fake parts! It's hard to spot. These even came in Toyota Genuine Parts box. See in photos. How to spot a fake: SM-J737T1 ?
I never go with Denso plugs. Why run with the second string when you can go with the varsity team (NGK)
DENSO Corporation is a well-established spin-off of Toyota Motor Corporation (TMC), it is Japan's leading producer of automobile components and the world's fourth largest. As the second-largest member of the Toyota Group, more than half of DENSO's products go to Toyota Motor Corporation (TMC), which owns better than 20 percent of DENSO stock. Considering this, I would have thought DENSO plugs would be the plug of choice for a Toyota, not second string.
