If we ignore a very brief period of automotive history, we find that most cars are made with efficiency in mind. Getting the most performance out of the motor has always been the name of the game. That task would be impossible without an efficient cooling system and by extension an effective radiator cooling fan.
When the cooling system, or one of its components fails, your engine is minutes away from catastrophic damage. Another thing that happens is the P0529 check engine light code. Join us as we dig into the meaning of this code, what causes the fan speed sensor issues, and how you can potentially fix it at home.
What Does P0529 Code Mean?
P0529 code is defined as Fan Speed Sensor Circuit Intermittent. In other words, the ECU has logged an interruption in the feedback from the fan speed sensor. Fan speed sensors tell the ECU how fast the radiator fan is spinning, and if it’s engaged at all. Without this sensor, the ECU is essentially blind to what the active cooling is doing. Naturally, this can be a problem.
Where is the Fan Speed Sensor Located?
In most cases, the fan speed sensor is located on the radiator fan assembly somewhere near the motor and the cooling fan clutch. Getting to it usually means removing the fan and breaking it down.
The fan speed sensor works by running a current through a filament strip and then measuring the effects of perpendicular magnetic fields on that strip. It’s a relatively simple and robust device, but it does fail from time to time.
What Causes the P0529 Code?
The silver lining to the P0529 code is that there aren’t too many things that can cause it. Here’s that short list of things to pay attention to:
· Bad fan speed sensor
· Fan speed sensor wiring issues
· ECU failure (rare)
If you focus on these three, you’ll solve the issue 99% of the time. Sometimes the issue could be in the fan motor, but that is usually followed by other diagnostic codes such as the P0480 or similar.
Bad Fan Speed Sensor
Fan speed sensors don’t fail too often, but they’re no more impervious to malfunctioning than any other part of your car. However, it doesn’t necessarily have to be a bad sensor. You could be dealing with a loose one. Vibrations from the engine, less-than-ideal roads, and such can sometimes dislodge the sensor just far enough for it to log codes.
Wiring Harness Issues
Wiring harnesses are generally made to last the lifetime of the vehicle. However, they are known to fail under extraordinary circumstances.
Physical damage, corrosion, heat damage — all of these things can greatly affect the integrity of the connector and any associated wires. Seeing how the ECU is looking for voltage changes in the circuit, a short somewhere in the harness can send a signal that the sensor has failed.
ECU Failure
ECU failure is one of those things that happens so rarely that people don’t even suspect it. Yet, if everything checks out, from the sensor to the wiring and potentially fuses, the last stop is the ECU. Due to how rarely these kick the bucket, we suggest that you investigate every other potential cause before you start looking into this rather delicate computer.
Common Symptoms of P0529 Code
The symptoms of the P0529 code are fairly straightforward and few. However, the main symptom of this code can be rather dangerous for the engine. With the ECU blind to what is going on with the fan, there is a lot of room for miscalculations in engine cooling. Here’s what you should be looking for:
· Check engine light
· Overheating issues
Overheating Issues
For the sake of brevity, we’ll skip right ahead to the second and most indicative symptom. With no control over the fan speed sensor, you might experience engine overheating problems. This doesn’t necessarily mean that your engine will overheat to the point of warping the head, but it could run hot, much hotter than usual. It also doesn’t help if the coolant inside the system is old. Replace your coolant every few years to keep everything in good working order. Check out our selection of engine coolants for a good option for your car.
How to Diagnose and Fix the P0529 Code?
Diagnosing the P0529 code comes down to checking the wiring harness, the sensor itself, and finally the ECU if you’re so inclined. First thing first, plug in the OBD-II scanner and read the codes. Run a full scan of the vehicle.
That is the only way to get the complete picture of what’s going on. Sometimes you can get several codes all at once, which might point to a completely different issue than what’s apparent.
Visually Inspect the Sensor and Harness
Before you start probing anything, it’s a good idea to give the potential suspect a quick inspection using your Mk.II eyeball. Look for any loose connections, and check to see if the sensor is fully seated and firmly in place. Follow the harness from the sensor back to the main line and look for signs of physical damage.
If everything looks fine, disconnect the connector and take a peek at the leads. Are they corroded, damaged, or melted? Check for any signs of debris that could hinder the connection at the connector. If everything looks fine, get your digital multimeter out. It’s time to start probing stuff.
Wiring Harness Test
The best way to check the wiring harness is to measure the resistance in every line that goes to the sensor. This means finding the right pin on the ECU side, disconnecting both the ECU (or PCM depending on the vehicle), and then measuring the resistance in that wire.
Do this for all related wires (power, signal, ground). Any readings out of the ordinary, or higher than 0, are indicative of an issue with the wiring harness.
Check the Sensor
To check the sensor, disconnect the connector and measure resistance between the power, signal, and ground wires. Again, you’re looking for no resistance. If you’re reading anything higher than 0, you might have an issue with the circuit on that side. The easiest thing to do is replace the sensor. Keep in mind that you might have to replace the whole radiator fan assembly depending on what you drive. Check our selection of radiator fans for quality replacement options
Can You Drive with the P0529 Code?
The answer is maybe, but you definitely shouldn’t do this if you can help it. Even if your engine isn’t reaching critical temperatures, you can still cause all kinds of problems by having it operate at higher temperatures than it was designed for.
Get Quality Parts and Fix the P0529 Code!
Fixing the P0529 is much easier if you have the right parts by your side. Here at eEuroparts.com, we stock some of the highest-quality spare parts for European vehicles. Our catalog includes genuine, OEM, and aftermarket parts made by world-renowned brands. To find what you’re looking for, head over to our shop section and select your vehicle using our navigation tool. Our system will return only the parts that are a guaranteed fit for your vehicle.
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