Q&A

 Rookie

Check Engine Light came on accompanied by rough idle and 3 shops told me Cat replacement was needed. Estimates all close if not exact. Went to the one closest to home and their analysis concluded that cat failed due to bad O2 sensors. Replaced Cat and O2 sensors. Light came back on within a few days. Returned and they reset the light and said to watch it for a while, they would replace Cat if light came on again. No further light, but rough idle getting worse. Returned to have them check it again, and they said problem was 2 cylinders with very low compression, possible valve job required. Took it back to one of the original 3 shops and they saw no indication of compression problem (didn't do a compression check, just saw no signs). They could see new Cat/O2 sensors and assumed those were OK. MAF readings extremely low, so replaced. Rough idle continued and further check by them indicated "FUEL TRIM READINGS ARE VERY LEAN. THIS IS FROM THE O2 SENSORS AFTER THE CAT GIVING FALSE READINGS DUE TO THE CAT". They suggested cat replacement may have been "less than OEM quality" and that I should return to the shop that installed it and ask for a replacement. $1563.69 so far, and other than no current check engine light, no improvement. What am I missing and what should I do next?