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Chris (aka-Moose)
Chris (aka-Moose), Auto Technician
Category: Toyota
Satisfied Customers: 901
Experience:  16 years of experience
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With my 2007 Prius (170k miles) I started getting the CEL

Customer Question

With my 2007 Prius (170k miles) I started getting the CEL with code for cylinder one misfire, intermittenly, then consistently last weekend. My mechanic changed sparkplug in cylinder one yesterday and noted it was very gunky. The CEL stayed off yesterday but came on again on a trip home at the end of the night. He read the same code today, did not see anything of concern with the engine; however, he thinks carbon is possibly building up and recommended putting in a small amount of Techron to clean the fuel injector. I am reading mixed things about adding Techron or other additives to a hybrid. I would like to try it once, though, as long as it is not a danger to the car.
JA: Does the light stay on, or does it blink?
Customer: stays on It is actually off again this morning
JA: Are you fixing your Prius yourself? What have you tried so far?
Customer: The mechanic changed the spark plug in cylinder one. He also switched the coils in cylinders two and three
JA: Anything else you want the mechanic to know before I connect you?
Customer: I have only owned this car for a year, and I replaced the hybrid battery shortly after I bought it
Submitted: 15 days ago.
Category: Toyota
Expert:  gomi_otaku replied 14 days ago.

Unknown why he swapped the 2-3 coils- I would think you would swap cylinder 1 with another cylinder, and swap the spark plugs with a different cylinder, redrive and see if misfires change to a different cylinder.

Additives are not going to cause a problem- the engine in a hybrid system is still a gasoline engine just like any other and is separate from the hybrid systems, it just produces the electricity to charge those systems and the battery.

Customer: replied 14 days ago.
Thanks! I will check to make sure I have the correct information on the switches he made with the cylinders; maybe he did switch 1 with 2. Makes sense. Very much appreciated, and have a good day!

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