Hi all,

My Japan-spec 1991 4.0 (AJ6) early facelift has started intermittently showing the 'EXH TEMP' light on the dash. I wondered if anybody has experience of this circuit and how it works? I feel like given the age it's probably as likely that the sensor or circuit itself is playing up as this being an actual error state, and given that these lights appeared only on Japan models as far as I'm aware and I'm getting no other fault indicators I'm hoping it's not a major thing. Would love to get to the bottom of it though.

Anyway, before I get stuck into it, does anyone have any experience with this issue? I don't know if it's a completely separate sensor specifically for this purpose (and where that would be located), or if it takes a signal from another sensor already used by the engine management ECU. In all the docs I can find online (1992 electrical guide and model update docs) there seems to be no mention at all of this system or of the warning light itself. Bit of a mystery. Would really appreciate any info!

All I can find online is this listing for a part DAC5955.

Thanks,
Matt

 

It should be thermocouple in the exhaust right after the catalytic converter. Looking at the later diagrams it shows the thermocouples going to a module and then to the warning light. I had one retrofitted to a Daimler and it would come on occasionally after a motorway run and then if I pulled off for fuel it would come on for a moment after restarting when things were heat soaked.

It might indicate things are running rich and the catalytic converter is having to process more fuel in the exhaust and running hot? Thermocouples don't last forever either, I think they are a standard K type thermocouple. The ones on the later X300 cars are a K type.

 

Hi there! Thanks so much for this info, that's exactly what I was after. I'll get it on some ramps and have a poke around! Thanks again