What is function of knock sensor in toyota 4-runner


Asked by Apr 16, 2015 at 08:49 AM about the 2005 Toyota 4Runner Limited V6 4WD

Question type: Maintenance & Repair

2005 4-Runner runs rough on start and then check engine light comes on with VSC
tracking lights. Wondering if it could be knock sensor and what is the function of a knock
sensor.After a few seconds to a minute, the super rough running engine smooths out but
light stays on. Someone also mentioned oxygen sensor.

2 Answers


Was just on a 4 runner forum. They say that if there is an error code, the VSC light will illuminate because the ECU shuts it down. Here is what the guy had to say: I want to share my experience with "Check VSC System Warning" that came on my dashboard about a week ago. I noticed that the warning Check VSC System came up while driving one day. I used my Obd2 scanner and ran the diagnosis and it came up with the code P0306, Cylinder 6 misfire detected and a check engine illuminated afterwards. Car would jerk while idling and would hesistate while speeding off. After careful study I narrowed the fault to possibly bad spark plugs. I learnt that the engine disables the VSC System when it starts loosing power. I went ahead to change the spark plugs. Now that is the interesting part; the plugs for the 2.4L 4cyl engine is different from the ones for the 3.5L 6cyl engine. The right plugs are FH20KR-11 and it was quite a challenge finding it. I got it and changed all the six plugs and cleared the codes. I drove for about 2km and the check engine light came up again together with the check VSC System warning. I got home and scanned the car again, this time around it came up with P0356, Ignition Coil 6 Primary/Secondary Circuit. I went ahead to replace the ignition coil on cylinder 6. After changing the ignition coil and clearing the codes i decided to test drive my car and it came back to life, full 268hp V6 power. It was quite an experience!! I also read where it could very well be a bad O2 sensor. That will cause the CEL to illuminate, thus disabling the VSC. I doubt it's a knock sensor issue. You should hear engine noise and it should be running quite bad. Like getting misfire codes.

2 out of 2 people think this is helpful.

Excellent explanation Reelin68. A knock sensor is a sort of microphone, that 'listens' for when detonation happens inside a cylinder and aids the ECU in ignition timing. The fault code is P0325 ..or P0326 bank one or a single bank engine, P0332 for bank 2 in a V6 Toyota

2 out of 2 people think this is helpful.

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