Hi all,

I've had this prob with my 2nd gen (V6) since i bought it 7 months ago, everytime i go over about 140km/h, the check engine light comes on.... it also comes on when i hold the revs too high for too long. Eg. if i redline each gear, it generally comes on.

So i reset my ECU, and ran it to 150km/h, and then connected up my test light thingy to the ECU - and it did its flashy code thing, and reported the Vehicle Speed Sensor and Knock Sensor as the problems. Now, is this bad? Is it faulty sensors, or something actually wrong with the engine? And wat exactly are these sensors?

I just dont know how to interpret it, and wat to do about it :cool: Help!!

Thanks guys,
Shane.

my understanding is the vehicle speed sensor has something to do with the emission control system and the knock sensor tells the ecu if the engine is getting pre detonation (fuel mix ignites before spark is fired) and accordingly retards timing.

Worth getting checked out

Hi all,

I've had this prob with my 2nd gen (V6) since i bought it 7 months ago, everytime i go over about 140km/h, the check engine light comes on.... it also comes on when i hold the revs too high for too long. Eg. if i redline each gear, it generally comes on.

So i reset my ECU, and ran it to 150km/h, and then connected up my test light thingy to the ECU - and it did its flashy code thing, and reported the Vehicle Speed Sensor and Knock Sensor as the problems. Now, is this bad? Is it faulty sensors, or something actually wrong with the engine? And wat exactly are these sensors?

I just dont know how to interpret it, and wat to do about it :cool: Help!!

Thanks guys,
Shane.

Firstly, speed kills. Remember that when youre going over the legal speed limit :)


The Vehicle Speed Sensor (VSS) is used for 2 things. Firstly for your Speedo, so a) you know how fast youre going, and b) to calculate ODO and Trip meter readings. Secondly, it is used for the ECU to determine DECEL and ACCEL conditions, as well as any other compensation tables it may run, such as lean cruise. No idea where the VSS sensor is located in a Magna. Maybe someone can teach me something there. On Most RWD cars, it would be found on the output shaft casing on the back of the transmission.

The Knock Sensor is used by your ECU to figure out how much timing advance it can run before causing pre-ignition (Aka, pinging, detonation, knocking, pinking). The ECU will progressivly advance its timing until the knock sensor reports pre-ignition, and then it will back the ign timing back. The logic for Knock Sensors varies between manufacturers. Some will actively try and get more and more advance, some may not use it so actively. The knock sensor is usually ignored at WOT and high engine speeds.

Is your car broken? Nah. Maybe check that you dont have a broken wire, resulting in an open or short circuit. Without the Knock Sensor, you may be robbing yourself of a bit of power and economy. The VSS error is possibly due to a worn gear in the VSS. These should be able to be replaced easilly.

Thanks for that, thats excellent news - ok, so the speed sensor i will talk to a mechanic about to find out cost of replacement etc etc, but the knock sensor i am still concerned about - if it is failing/not working correctly, will running my car at high revs/speeds damage my engine?

Thanks for that, thats excellent news - ok, so the speed sensor i will talk to a mechanic about to find out cost of replacement etc etc, but the knock sensor i am still concerned about - if it is failing/not working correctly, will running my car at high revs/speeds damage my engine?

Listen out to see if you can hear it pinging. That is going to be your only issue. If its not pinging, its no problem.

Speak to your local Auto Electrician about it.

cheers mate, i shall do just that.

Tell your mechanic that a code 24 is the speed sensor, code 31 is the knock sensor.