Cooling fan FUNCTIONALITY failure.
1st ensure the fans, both of them are coming on when the vehicle gets hot. This code is set after the ECU triggers the fans to come on, the temp as read by the engine temp sensor has NOT decreased in the 'specified' amount of time.
Fans not running, suspect fans, relays, fuses to the fans, ECU
Fans running, ensure there are no obstructions before or after the radiator. Also the radiator may be clogged. Or if vehicle is not overheating it can be a defective engine temp sensor.
Hope this information helps you find your problem.....remember the 98 has the N/A DOHC which is also prone to head gasket failure, so it you ever see coolant spewing out of your reservoir after a long run on the highway, this is one symptom of a failed head gasket.
98S, 2014 Impreza 5 dr Ltd (9 Subaru's since 1978, 7 were 5 sp) ILuvSubaru's