Toyota Repair: 89 MR2-check engine light, toyota mr2, jumper wire

Question
Hi, i got a 89 toyota mr2,  I washed the engine to see where a oil leak is coming from,  the washer in the distributor was replaced and solved the problem.  Now the check engine light when on.  I am thinking of the replacing the oxygen sensor. I am i on the right track or should I take the car to a local shop to run a diagnostic?  Appreciate any advise.
Thanks.


Answer
The first step would be to retreive the diagnostic trouble code, this can be done by locating the diagnostic check connector under the hood, identify terminals TE1+E1, then place a jumper wire between these two terminals of the connector, turn the key on and then count the number of times the check engine light flashes, it will be a two digit code, for example a 25 code would be two flashes followed by five and so on. The code number can then be looked up in a diagnostic trouble code chart to see what the problem may be.