I have a 2013 Prius C with about 220,000 km on it. The check engine light is on, but that has been on steady prior to this. I put a code reader on it but it was a cheapy, and I could not read the hybrid codes. It ran fine so I did not do anything about it. A few months ago we noticed that the traction control light would sometimes come on, even when the roads were dry. Then it started that other warning lights would come on. The red and orange (!) ones. The traction control and ABS. They would stay on for a few minutes then go off. It seemed to happen more in wet weather, but I cannot be sure on that. Now they are on all the time, but the car seems to run fine. I am wondering if its a connector that has become corroded? A mechanic told me there is a connector near the rear of the car that often is problematic. Image attached. Any thoughts?
Other than the check engine light, having what seems like almost every other warning light come on is often triggered by a loss of the signal from one of the rear wheel speed sensors. It could be the sensor itself or a corroded connector to the sensor.
A bad wheel speed sensor is plausible. The car relies on accurate data from all four wheel speed sensors for a few different functions including antilock braking and traction control. This isn't a real diagnosis, you'll still need to confirm this, but it fits with age & wet winter driving.
They're called warning lights, so having them come on while "the car still runs fine" is what you want. Coming on only after you can tell the car's not working would be a little late for warnings. So the key is just to find out what the car is warning you about. That means the trouble codes. This way doesn't work for all trouble codes in the car, but it does work for the brake/ABS/skiddy-car lights: Blink (a/k/a Flash) Codes – How to. | PriusChat Once we know what the car thinks is going wrong, we can think about whether it's right about that, or whether some sort of connector issue, etc., could be making it think that. No sense trying to figure that out before even asking what the car thinks.
How much would dealership charge to read the codes? Don’t ask? still, seems like the best bet for resolving the uncertainties.
Agree with others that it might be a wheel/abs sensor issue. There would be no changes in how the car/engine runs, but if the sensor has gone bad or even just developed a connection issue, when the lights are on you should notice a change in how the breaks feel. They will still work, but there would be subtle differences such as as a slight mushy feel or having to push the pedal a little further or harder to engage the breaks. I recently had tires replaced, and driving off after it was done, those same series of lights came on, although they later went off, and for a few days they would come on and off at random intervals. But each time they were on, the brakes behaved differently, as I described above. Eventually they went off for good and all was normal. I'm guessing maybe some rust got shaken loose during the the tire change effecting the wheel speed sensor cable connection, and after a few days it moved again restoring full contact, but who knows. Do the brakes feel normal?
