Peugeot 408 Water Sensor Fault

Greetings. A defective water sensor can certainly cause those symptoms in your Peugeot. The water sensor, also called a coolant level sensor, monitors the amount of coolant in your system. A fault like this can trigger the check engine light and affect engine performance. Have you inspected the sensor and its wiring for any obvious damage or corrosion?

Yeah, I had a peek. Couldn't see anything obvious, but I'm no expert at spotting dodgy wiring. Is there a proper way to test the sensor, like with a multimeter or something? I'm trying to avoid a big bill!

While a multimeter can be used to test the sensor's continuity and voltage, diagnosing sensor issues can be tricky without the proper diagnostic tools and knowledge. Given the potential impact on engine performance, and the stored error codes, I would suggest a workshop visit. Don't want to risk further damage.

Thanks! Took your advice and went to a workshop. You were spot on - turned out to be a corroded connector on the water sensor. 95€ later and it's all sorted. Appreciate the help!