[Mk2] [Turbo] Strange knock sensor problem

[Olly P]

Hi guys, wonder if you might have done ideas on this.

My Rev2 turbo runs at 14psi (ct20b, bolt ons, 99ron fuel etc). Last month I suddenly got error code 52 - knock sensor. Thought this was strange as I've not changed anything on the car for at least a year. Anyway, I replaced the knock sensor, reset the ECU, and the following day the engine management light came on again, limp mode, error code 52 again. Grrr!

However, I can turn the engine off and on again and the car will no longer be in limp mode. It's almost as if the knock sensor has fixed itself! I can use full boost for days, but then randomly when cruising along, the engine management light will come on again and I'll be in limp mode again. Restart the engine and it fixes itself.

Normally when you get error code 52 it means the knock sensor has failed and the car will stay in limp mode until the sensor is replaced.

So what's happening in my case? It all seems a little odd.

[bobhatton]

Hi guys, wonder if you might have done ideas on this.

My Rev2 turbo runs at 14psi (ct20b, bolt ons, 99ron fuel etc). Last month I suddenly got error code 52 - knock sensor. Thought this was strange as I've not changed anything on the car for at least a year. Anyway, I replaced the knock sensor, reset the ECU, and the following day the engine management light came on again, limp mode, error code 52 again. Grrr!

However, I can turn the engine off and on again and the car will no longer be in limp mode. It's almost as if the knock sensor has fixed itself! I can use full boost for days, but then randomly when cruising along, the engine management light will come on again and I'll be in limp mode again. Restart the engine and it fixes itself.

Normally when you get error code 52 it means the knock sensor has failed and the car will stay in limp mode until the sensor is replaced.

So what's happening in my case? It all seems a little odd.

Code 52 resets every time you turn the engine off.

Check the wiring to knock sensor, replace the knock sensor with a new Toyota one and set your timing to no more than 8 deg BTDC

All JDM turbo car are running under the control of the knock sensor as our fuel is not as high an octane as the engines were designed to work with.