If you have a Toyota vehicle with COP (Coils over Plugs) and you have all these codes stored- P0351,P0352,P0353,P0354,P0355 andP0356 Ignition coil Primary/Secondary Circuit, check and see if you have any aftermarket coils installed on the vehicle that may be causing all these codes. I will include some links below for you to look at about Toyota ignition systems but as a really quick/basic overview I say this... older Toyota vehicles used signals NE (Crankshaft signal) and G (Camshaft signal) to create IGT (Ignition signal, "I got timing") and once ignition took place, IGF (Ignition finished, "I got fire") was the signal to the computer that the cycle was completed. Here is a better explanation of the Toyota Ignition System... The current style Toyota COP system is explained on page 8 of 12 in the link above. Keep in mind that the engine in question for our 2013 4Runner is a 6 cylinder and has only one IGF line for all 6 coils. The explanation in the Toyota ignition system in the link is a 8 cylinder and have 2 IGF lines (IGF1 and IGF2). Just one bad aftermarket coil can disrupt the IGF line signal to the ECM for all the coils and thus show many fault codes when in fact just that one coil is the root cause. The reason that the aftermarket coil was cheaper is for a reason. Just make sure that you are using Denso brand plugs and coils on your Toyota vehicle. I hope this helps you.