Chrysler Repair: 1995 Chrysler Cirrus, chrysler cirrus, 1995 chrysler cirrus

Question
I have a 1995 Chrysler Cirrus that is making me lose my mind.  For several months the check engine light has come on.  I have had the car serviced several times. Repairs include, New Air Filter, o2 sensor front bank replaced, new thermostat, fuel injectors blown out, heater core blown out. Just had the car in for service yet again due to sluggishness and horrible gas mileage, and the check engine light is still on despite all of the repairs, and now my ABS light is on.  Mechanic tells me that he gets no reading/codes on his computer, engine runs beautiful, he only had to adjust linkage as there was no kick down.  My husband ran the key on off and got the codes 122 and 155, 155 is an ETC error
and man do I need help, my manual does not explain the ETC error.  Any thoughts, suggestions or help would be so greatly appreciated.
Thank you

Answer
Hi Laura,
First off, the codes are actually two digit numbers, not three. So what your husband read was actually 12, 21, 55.
The engine light coming on means there is a stored code that effects the driveability. The problem is that the codes he read may or may not be relevant at this time because the codes stay in the computer unless they are erased by the tech when he services it, or the repair is effective and you then have also cycled the key on-off 50 -100 times without the code recurring. The easy way to erase the codes is to disconnect the battery while the head lights are on (just unclamp the -post), then turn off the headlamp switch, then wait 5 minutes, then reconnect the - post clamp. Then reread the codes, you should get only a 12 (battery disconnected recently) and a 55 (end of readout).
There should be no 21 if you haven't started the car up.
Then start and run the car a few times; assuming the check engine light comes on again, if you then reread the codes there will be an additional code (other than the 12 and 55). If it is the 21 code back again, then that says the O2 sensor is still not sending a signal about what is going on with the mixture so the engine controller then defaults to a fixed mixture mode that will cause poor mileage but keep the engine running. So then I would go back to whoever put in the new O2 sensor and tell them that they goofed and to check the new sensor and its wiring to the engine controller. If it is some other code, let me know. The read out of codes is in serial order so it would come out as (in flash counts): 1,2,2,1,5,5 if what I have postulated is in fact what you find.
Roland