All 2012 Scion IQ up to 2013 JTNJJXB0#DJ025093 were built with defective pistons. If you are thinking of buying one, unless a seller can prove they have had this work done, be prepared to spend $4.5K to have the pistons replaced. See service bulletin S-SB-0032-13. Toyota made me make a "good will" gesture of $1900 toward this repair. All of these cars should have been recalled. There's … about 11,500 2012 - 2013 IQs involved. Outrageously dishonest of Toyota.
I tried to apply the $1900 "good will" gesture toward purchasing the parts (I am capable of installing them myself) but Toyota would not agree. Even Toyota's mechanic thought they should have recalled the 11,500 cars in question and tried to help me get the repairs paid for by Toyota. Finally, I had Toyota replace the pistons. Toyota did pay the $1900. I paid the remaining $2000+. The car was using a quart of oil every 400 miles just before the repairs were made. Replacing the pistons corrected the problem. However, shortly thereafter the catalytic converter failed (plugged up from the high oil consumption). I bought the catalytic converter and replaced that myself for about $400. It would have been $1000 if I let Toyota do it. All these parts (pistons, catalytic converter, etc) are proprietary. You can only buy them from Toyota. You are at their mercy.
Now, 30,000 miles later, the car is running strong and getting 35 - 37 MPG. I still like the car. Three months after the Toyota repair a Toyota representative called me up and gave me a verbal spanking for not paying the entire amount and waiting for Toyota to reimburse me the $1900. The Service Department had agreed to the way we handled it. I told the woman I would NEVER BUY ANOTHER TOYOTA new or used and that I am having a good time spreading the word on their terrible customer policies. I had a sign shop make a professional sign for the back window stating "Beware of 1,000's of Toyotas with Defective Pistons, Google it." I drive 100 miles a day in the Dallas, Metroplex. 1000's of people have seen that sign and dozens have asked me about it. I have all the paperwork and a nice picture of the car with the sign in front of their new headquarters building. You can see the picture on my FaceBook page. I guess after building that lavish new headquarters they can't stand the cost of standing behind their cars. You should Google Toyota defective pistons and see what comes up. It wasn't confined to just the Scion IQs. There are many, many more Toyota models with the problem.
Review update 08-15-18: Car is running fine. Now at 171,000 miles, uses no oil. I still like the car but I will never buy another new or used Toyota because of the way I was treated. Five months after it was fixed a representative called me. They were not happy that the service manager allowed me to only pay the difference between the engine work cost and the $1900 "good will" gesture at the time the work was done. This made it easier for me to not come up with another $1900 and then have to wait to be reimbursed. I was shocked and it just reminded me how much I disliked how I was treated. I spent $75 and had a sign shop make a nice full rear widow sign that said "Beware of Toyotas with Defective Pistons." You can see it on my FaceBook page setting in front of the new Dallas Toyota Headquarters. I drive 100 miles a day through Dallas everyday. I know thousands of people saw that sign and it makes me feel much better. Screw 'um!
Update 2-15-19: After replacing pistons at an out-of-pocket cost of about $2.5K, the car is running fine at 181,000. No other problems. I won't, however, be buying any more Toyotas.
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