[eclecticist]

My car, 93 3vz-fe, is reading a check engine code of 28. This code is not in my Haynes manual and my local Toyota dealership will not tell me. They said I should bring it to them for a ~$60 USD diagnostic.

I did a Search but found nothing on this problem.

Does anyone know what this code means? Thanks.

 

[88 LE]

Not sure what 28 is.

27 is sub-oxygen sensor signal.

When sub oxygen sensor is warmed up and full acceleration continued for 2 seconds, output of main oxygen sensor is 0.45 V or more (rich) and output of sub-oxygen sensor is 0.45 V or less (lean).

1. Short or open in sub-oxygen sensor circuit.

2. Sub-oxygen sensor

3. ECM


My guess is that you have a bad O2 sensor.