Volvo: volvo 240 91, volvo 240 91, brake warning light

Question
this car is driving me nuts..coolant temp sensor change but
code 123 still comes on..try clear it several times including removal of battery.then light will re-appears. Also brake warning light comes on at hard braking.calipers,master cyl and pads replaced..

Answer
Gord,
The temp sensor that is for the fuel injection is at the rear of the head. Is that the one you changed? Make sure that the wire connectors are clean and tight.
Replace the brake valve bleed all wheels and see if that will get rid of the brake warning light.