Frontier exhaust temperature sensor fault

Yep, a faulty exhaust temperature sensor can definitely trigger those symptoms. The ECU uses that sensor to manage the engine. If it's giving bad readings, the ECU might reduce power and increase fuel consumption as a precaution. Any chance you've checked for exhaust leaks?

Exhaust leaks, huh? I haven't specifically looked for those. Where would I even start to check? Is it something I could potentially fix myself, or am I better off taking it to a shop?

Leaks can be tricky to spot without proper equipment. Sometimes you can hear them, like a hissing sound, but not always. Given the sensor code and your symptoms, a leak is a likely cause that's messing with the readings. I'd advise getting it checked by a workshop; they'll have the tools to properly diagnose and fix it. Exhaust work often needs welding, and a professional can ensure a proper, safe repair.

Thanks for the help! I took it to a local shop, and you were spot on – it was a small crack in the exhaust manifold causing the sensor to give incorrect readings. They welded it up and replaced the temperature sensor, total cost was 265€. Runs like a champ now!