Silverado diesel PTC heater problem

Sounds familiar! I had a similar problem with my older BMW 3 Series – different brand, same headache. Cold starts were rough, and the fuel consumption went up noticeably, especially in winter. It wasn't a PTC heater issue (it was the glow plugs), but the symptoms sound really similar. Did you check the heating element's resistance? An open circuit would definitely throw a code and mess with the engine's cold start strategy.

Thanks! When you say check the heating element's resistance, do you mean the auxiliary heater element itself? If so, where would I find the connector to test this resistance? I want to be sure I'm testing the right thing.

Yes, I meant the auxiliary heater element itself. On my BMW, it was hard to get to, near the blower motor. Since it's a PTC heater, it should be between the main heater core and the ventilation system. Honestly, with the error code and symptoms, it might be easier to take it to a shop. My problem cost me around 250€ to diagnose and fix (glow plugs and labor), so it might be worth getting a professional opinion before you start tearing things apart.

Understood. I took the Silverado to a shop, as you suggested. The electric auxiliary heater was defective, as suspected. The repair cost, including parts and labor, was 350€. Replacing the PTC heater fixed everything. Thanks again!