What does it mean?
Some vehicles are equipped with a sensor at the end of the cooling fan that detects movement during vehicle operation. The sensor is used to determine if the fan is operating on a vehicle equipped with a fan clutch or to verify that the fan speed commanded by the Powertrain Control Module (PCM) or Engine Control Module (ECM) matches the actual fan speed detected on a vehicle equipped with an electric fan.
The sensor used is a 3-wire Hall effect sensor that uses a 5-volt reference source from the PCM, a ground wire, and a signal wire to the PCM to determine the fan speed. Specifically, a P0529 fault code means that the PCM/ECM is not receiving a stable output voltage from the fan sensor’s signal wire.
Note: Be careful not to touch an electric fan, as it may turn on even when the vehicle is not running. This code is similar to P0526, P0527, and P0528.
Symptoms
Symptoms of a P0529 DTC may include:
Illumination of the Malfunction Indicator Lamp (also known as the Check Engine Light)
The vehicle may overheat or run hotter than normal
Causes
Potential causes of a P0529 code include:
Loose connection in the cooling fan sensor harness or the PCM/ECM harness
Faulty PCM/ECM
Faulty cooling fan speed sensor
Possible Solutions
Cooling Fan Sensor Harness – Check for loose connections and damaged cables that may have come into contact with the cooling fan. Disconnect the cooling fan sensor connector and the PCM connector and check the resistance using a Digital Volt-Ohm Meter (DVOM) with leads at each end of the power cable, signal cable, and ground (if they are connected to the PCM/ECM). Some car manufacturers have issued a Technical Service Bulletin (TSB) for replacing the sensor cable harness. Replace or repair the harness.
PCM/ECM – Disconnect the fan speed sensor harness and the PCM/ECM harness. Using a DVOM with positive and negative leads connected to each end, check for excessive resistance in the signal wire circuit. Back-probe the signal wire using a DVOM set to the volts scale or a graphing multimeter on the sensor harness and the PCM/ECM, with the positive lead on the signal wire and the negative lead on a known good ground, to determine if voltage is present from the fan speed sensor. If the signal voltage is steady and increases with increasing fan speed, suspect a faulty PCM/ECM.
Cooling Fan Speed Sensor – Check the sensor mounting at the end of the cooling fan assembly for a loose mount or a loose connector. Disconnect the sensor harness connector and test for continuity using the DVOM set to the ohms scale between the power, ground, and signal wires; no resistance should be present between the signal wire and the ground or power wires. If resistance is present when manually rotating the fan, there may be an internal short circuit.
The signal wire can only be tested during actual fan operation by probing the harness connector with the DVOM set to the volts scale, or a graphing multimeter with the positive lead on the signal wire and the negative lead to a known good ground, since the Hall effect sensor used operates by creating a magnetic field that changes the voltage while the fan is spinning. As the fan speed increases, the voltage should also increase. Replace the cooling fan speed sensor if the wiring is good and the signal voltage sometimes drops.