P0528 Radiator fan: no signal (speed sensor)

By: Diagno editorial team · Updated: 2026-10-15

P0528 means: Radiator fan: no signal (speed sensor). The radiator fan cools the engine when airflow from driving isn't enough. Drive gently and have the car checked soon. The most common repair costs about €45–90 in Estonia, depending on make and model. The most common cause: connector loose, damp or corroded.

What it means

The radiator fan cools the engine when airflow from driving isn't enough. The computer found a fault in the fan control. The computer gets no signal at all from the part.

What you may notice

• The engine overheats in traffic or at idle
• The fan doesn't run or runs all the time
• The air conditioning cools poorly

What could be wrong

1. 1Connector loose, damp or corroded · Wiring or connector repair €45–90
2. 2Wire broken or chafed · Wiring or connector repair €45–90
3. 3Faulty fan or its module · Control unit check and software €150–300
4. 4Engine computer fault (rare) · Control unit check and software €150–300

Repair difficulty: Easy

What you can check yourself

First look at the connector and wiring: anything loose, melted or green with corrosion? Watch the temperature gauge. If it goes above normal in traffic, stop and let the engine cool. You can check the simple things yourself, but the repair is best done in a workshop.

How we fix it

1. We read the fault data on the diagnostic tool and check whether the fault is constant
2. We measure the circuit's supply, ground and signal
3. We repair the wire or replace the connector
4. If the wiring is fine, we replace the fan or its module

Standard SAE description: Fan Speed Sensor Circuit No Signal