Hi,

I'm reaching out regarding an issue I've encountered with my car's tachometer (RPM gauge). I hope someone might have experienced a similar problem or can offer guidance on potential solutions. I drive a 2005 Lexus GS300 (3rd gen). While driving, I've observed that the tachometer occasionally drops to zero, even when the engine is clearly running and maintaining a significant RPM. After a short interval, it rebounds and displays the correct value. I first noticed this during cold and wet weather today. It was crazy after I started the car, like it dropped to zero and bounced back few times a second. Once the engine warms up, the issue started to disappears, and the RPM gauge functions perfectly. Could the problem lie with the gauge itself, or might it be related to a signal issue from the sensor? If it's the sensor, could you tell me where it is located?

 

Sounds like a dirty maf sensor, very easy to clean. Just unplug the harness and use a phillips screw driver to remove. I would also clean the throttle body

 

But the car is working perfectly fine it is the only issue with gauge, you think its the MAF sensor? Its not like the car stopped working for a while just gauge pointer drops to zero

 

So you dont feel the rpms drop and that its only the tach that drops? If thats the case, maybe its a bad ground, or moisture in the fuse box. Some electrical issue. Could map also be one of the timing sensors, but I dont want you to guess and waste money. A good mechanic with a scan tool, can live data log all the parameters with the engine running. If a sensor drops it will show on the graphs

But I would still clean the maf and throttle as it doesnt take much time. Just incase to rule that out. Because a dirty maf can drop the rpms