I have a 1996 Civic EX sedan with automatic transmission (126,290 miles). The check engine light came on and the car was brought to the Honda dealer. Besides the check engine light I told the service advisor the engine idle was low and the transmission shifts were not smooth.

The technician diagnosed the error code as PO135 and replaced the primary oxygen sensor under the Honda extended emissions warranty. In addition, the distributor cap, rotor, and spark plugs were replaced. An engine oil change was also done without charge.

As far as the low engine idle, the technician said it was possiby due to a faulty idle air control valve. I was told since no error code came up for this problem, it would be $480 to replace this part. I advised them this part was listed as a covered part under the extended emissions warranty, but the dealer said since there was no error code displayed, I would be responsible for this part. I called the Honda Automobile Customer Service and they agreed with the dealer. Two questions: Is there a specific code to identify a faulty idle air control valve? Will any harm come to the engine if it is not fixed?

The rough transmission shifts were diagnosed as an internal failure of the transmission. The estimate of this repair was $2800. Two questions again: Are there any connections between the rough shifting and emission problems? I'm asking because there are a couple of transmission related parts (?) covered under the warranty such as A/T gear position switch, shift control solenoid valve, and lock-up clutch control solenoid valve. Should a transmission be replaced just because it doesn't always shift smoothly?

Thanks for any replies!

 

You can probably fix the IACV yourself by cleaning it (see forum DIY).

Also, try draining and replacing the transmission fluid with genuine Honda AT fluid. It could help.

As for codes, if the CEL turns ON again, take the car to AutoZone and have them pull the codes free of charge. You will then have an independent source tell you whether the IACV or transmission is throwing a code that may be covered by the extended warranty.