Like any component under the bonnet, coolant temperature sensors can develop faults over time. A faulty sensor can lead to a range of problems developing, including overheating and poor engine performance. That’s why it’s important to know how to spot the signs of a faulty or failing temperature sensor, before it can cause further problems which could prove more expensive to fix. Start by having a look at the unit itself to check its condition, as sensors/gaskets/connectors can develop cracks with extended use and continual temperature cycling. The CTS is usually found at the front of the car, near the thermostat housing, or on the radiator. While a visual check can help to diagnose some faults, not all problems with a CTS show visible symptoms. Some other symptoms include: Irregular reading of the dashboard gauge, overheating engine (highlighted by dashboard gauge), check Engine Light alert on dashboard, rough engine sound while idling, limited performance (caused by ECU miscalculating fuel rich mixture) and poor fuel economy. The CT sensor is a relatively manageable DIY job however, depending on the fitment position of the sensor in your vehicle, some other engine components may need to be removed to gain access. If you are unsure about carrying out a CT sensor replacement, consult a certified mechanic to avoid further damage.