thomyb

Hello,
I have a '92 ES300 and the engine light went on. I did the paperclip trick and the engine light flashed codes 52 and 55 which indicate knock sensor signals from both sensors. The engine runs nice, idle smoothly and seems to have the same amount of power as it always has had. I have not noticed any smoke coming out of the tailpipe and the engine runs at a good consistant temp. I turn the engine off and the light does not come back on until I get the RPM up to 2200-2500. This seems to happen more after the engine is warm. I highly doubt that both knock sensors went bad at the same time. I usually run 89-91 octane gas, but have had 87 in it in the past (I'll blame it on the wife). The wires and plugs were changed just a couple of months ago. I do not notice any ticking or clatter sounds in the engine at any RPM. I am looking for any advice as to why the light only seems to come on at that RPM range and what options I have other than yanking the CEL light and/or an engine rebuild. Thanks.

JSM1284

esucaris1

Mine did the same thing with the same codes I replaced the knock sensors end of problem...

Lexucan

^^ Same here. As soon as the RPMs hit the 2300-2500 range, the CEL would come on and the car would go into "limp mode" with very little power. It is rare that both sensors would go at the same time, though. Could be the insulation on your knock sensor wiring harness has become brittle and cracked with age and has shorted out, causing both sensors to malfunction. Maybe.

esucaris1

My sensor wiring was so brittle that the plugs disinagrated trying to unplug the sensors $45 at Toyota