How do you diagnose a coolant temperature sensor and oxygen sensor on a 1991 Hyundai Excel with 1.5L EFI Mitsubishi engine?
The best way is to find someone with a scanner that tells you what every sensor is doing.
Answer The coolant temperature sensor is located in the coolant housing on the transmission end of the engine under the ignition coil. In my experience, most of the problems with this coolant temperature sensor are intermittent, so attempts to troubleshoot usually prove fruitless. If you'd like, you can view the schematics for the vehicle in the ETM section at www.hmaservice.com. You'll need to register for a free account, and the site requires Internet Explorer.
Diagnostic error code number 118 with high temperature input on a Audi A4 means that the engine coolant is not running at the right temperature. When the engine is cold, it should be warm, and when the engine is warm, the temperature should be cooler in the engine. The problem could be with the Engine Coolant Temperature sensor or the vehicle could be low on fluid.
The heat stopped working on your 1993 Toyota Camry The radiator is not leaking the thermostat is good what else could cause this and how do I diagnose problem?
The Engine Coolant Temperature (ECT) sensor is location very near the thermostat. But this signal is sent to the Powertrain Control Module (PCM) - the control computer - which takes this information and drives the temperature gauge in the dash. So if you are having an issue with your temperature gauge, then you will need to diagnose the system, usually with a scan tool.