Hey Barnkat,



Thanks for posting in regards to this. I've had the same problem with mine. Code 1-4-3 and once it warmed up, no power. I replaced the knock sensor with a new one, instantly threw the code again. I found a copy of the Volvo green book regarding ignition systems, and this is the limp home mode of the Rex-1 ignition computer. Timing is fixed at 10 degrees with no further advance, regardless of engine speed. I think it waits till the engine warms up since it uses some default timing map when the engine is cold. I got a used ICU and the car runs ok now, but is still throwing the 1-4-3 code. However, it waited a while before it did. I have cleaned all my grounds short of the one at the PS pump. I think I may still have a grounding issue. I have also checked the knock sensor wiring. With the sensor lead shorted, I got a reading of .4 ohms, which is good considering all the light gauge wire. I also cleaned the connector at the strut tower. These ICUs are pretty reliable, but also seem to be easily damaged by voltage spikes (bad grounding, welding on car, etc) as you mentioned. I am sharing my experience more than asking for help, since this only seems to affect Rex-Regina cars, and is rare enough to make it hard to diagnose.

Regards, Jon