Tesla Model 3 PTC heater replacement: one failed rod, fixed before it became an isolation fault

Another urgent repair, completed at short notice to stop a fault turning into something worse.

This Model 3 came in with a failed PTC heater. The car was still driveable at the time, but a heater fault like this can develop into an isolation fault, and that can leave a car unable to drive.

What the PTC heater does

The PTC heater warms the cabin. It runs on the high-voltage system and heats up through a set of heating rods. Because it is connected to the high-voltage system, a failing rod is more than a comfort problem: if the fault gets worse, the car can register an isolation fault.

Parts in stock, booked in quickly

As with Model S battery heaters, we keep Model 3 PTC heaters in stock. That meant we could book the customer in quickly instead of waiting for parts. The day before, we did a similar same-day job on a Model S battery heater.

Pinpointing the fault

We started by checking the active alerts, then ran Tesla's compromised rod detection test. It confirmed that one rod inside the heater had failed.

The repair

• replaced the PTC heater unit
• carried out the required software redeploy after installation
• ran the compromised rod detection test again, which came back clear
• ran the HVAC performance test, which also passed

The customer now has the full heating and climate control system working properly again, with no related faults.

Why we test before and after

Running Tesla's own tests before the repair told us exactly which part had failed. Running them again afterwards proved the repair worked. It is the same approach we take on every job, from thermal system repairs to suspension work.

If your Tesla is showing a heater, climate or isolation warning, even if it still drives normally, send us a message and tell us what the screen says. Faults like these are cheaper to fix early.