QuestionThe engine light is reading codes number 12, 21, and then 55, which should be the end, but i lost the book, can you help me figure out what those codes are, that would help a lot, thanks!
AnswerHi Danielle,
The 12 means that sometime in the past 50-100 key on-off cycles that the battery power was disconnected. If that is not true to your knowledge then you might want to check the clamps at the battery for being clean and tight. Always remove the - post first, then the + post, then put back the + post, and finish with the - post. You might also check the ground wire from the - post to the body below the battery to be clean and tight and to the engine block similarly.
The 21 means there is no change in the signal from the oxygen sensor located on the exhaust manifold, either because its wires are damaged (inspect) or it has ceased to function (replace). This will cause either or both poor performance or loss of mileage.
The 55 meams simply "end of readout".
Roland
