Aaaargh...how Do I Fix This?

[Pogle]

For the last 12 months MIL light keeps illuminating (although car has never gone into "limp" mode). Code is always 0400 which is EGR. Removed and cleaned original EGR and it wasn't too mucky but no different so replaced it with an shiny new one - proper Denso original. Still no different.

Tried dollops of turbo cleaner and BG 244 etc without success. As a result of advice from another forum user I have also cleaned MAF (again no difference) and have now replaced this with a new unit (again original part) but no different. Diagnostic tests done by auto electrician and reports no faults with any of circuits/connections etc.

Does anyone have any ideas as that yellow light is properly getting on my pips now?

[Cyker]

Did you also check the throttle body when you did the EGR?

Usually the EGR gets a bit sooty but is otherwise fine, however the inlet port in the throttle body that the EGR is connected too seems prone to blocking up with soot on the D4D's.

[Devon Aygo]

I assume the issue is on your later Rav? if so the EGR is more than just the valve on the front of the engine there is a whole lot more to fitted to the back of the cylinder head including an EGR cooler, this is also prone to blocking and causing P0400, to fix either replace the cooler and clear through all the extra pipework or using a strong ammonia based cleaner soak and flush the cooler to remove the carbon buildup.

The www.toyota-tech.eu site ( paid access ) has instructions on how to diagnose and repair P0400 issues.

[Pogle]

Apologies didn't make it clear this issue is with the 4.2 d4d. What's this throttle body malarkey? The EGR I replaced was just bolted onto the side of the head/ block?

[Pogle]

Haynes manual refers to an EGR cooler pipe. Is that something that could be causing the problem if it is gunged up?