MBecky

Seat Toledo knock sensor issue

Hello, I'm experiencing some issues with my Seat Toledo from and it has a gasoline engine, and I'm hoping someone can offer some guidance. My car has about 195656 km on it. The check engine light came on recently, and I've noticed a significant increase in fuel consumption and the engine is idling unevenly. I scanned the error codes, and it indicates a defective knock sensor. I suspect it might be the cause of my problems. My limited understanding suggests that a defective knock sensor could mess with the engine's ignition timing, leading to these symptoms and potentially causing engine knock. I read somewhere that the most probable cause could be a defective cable or plug connection of the component and I'm praying that's the solution because I'm not ready to pay a lot for auto repair. Has anyone experienced something similar? Any advice on how to troubleshoot this issue further before I take it to a mechanic?

4 comment(s)

Hey there, I had a similar issue with my Seat Toledo, although I can't remember the exact year of manufacture, but it's a similar model. The check engine light was on and the engine was running rough, kind of like you describe. For me, it turned out to be a faulty knock sensor as well. Before you go replacing the sensor, have you checked the wiring and the connector? Sometimes, a loose or corroded connection can cause the same symptoms. The knock sensor's job is to detect engine knock, which is abnormal combustion that can damage the engine. When it detects knock, it sends a signal to the engine control unit (ECU), which then retards the ignition timing to prevent damage. If the sensor is faulty or the wiring is bad, the ECU might not be getting the correct information, which can lead to all sorts of problems, including poor fuel economy, rough idling, and the check engine light illumination. Ignition timing basically is the timing when the spark plug fires in relation to the position of the piston in the cylinder.

Thanks for your quick answer! I did a quick visual inspection of the wiring and the connector, and everything looked okay. But honestly, I'm a bit of a novice when it comes to auto repair. How can I properly check the wiring and the connector to be absolutely certain that's not the issue? Is there a specific tool I need, or a procedure I should follow? I'm trying to avoid replacing the sensor if it's just a simple wiring problem.

Given that you're not super experienced with auto repair and you've already checked the connections visually, I'd recommend taking it to a trusted mechanic. It's difficult to properly diagnose electrical issues without the right tools and knowledge. While a faulty connection is possible, a failing knock sensor is also a common problem. Better to have it properly diagnosed to avoid unnecessary parts replacements. You don't want to start replacing the wiring harness when the knock sensor is the problem for sure. A mechanic will be able to use a multimeter to check the sensor's output and the wiring for continuity. If your car is experiencing engine knock for real, continuing to drive with a faulty knock sensor might damage the engine.

Big thanks for the help! I went to the garage as you recommended. Turns out it was indeed a faulty knock sensor, just like we suspected. The diagnostic showed error code P0325. They checked the wiring and the sensor itself, and the sensor was the culprit. Cost me 95€ including labor. At least now the check engine light is off, it idles smoothly, and hopefully, my fuel consumption will go back to normal. Really appreciate your insights!

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