P0400 Error - Egr Valve

[stu_cole]

Good Morning

I had the EGR valve replaced 2.5 years ago and since then i've done about 45,000 miles with a lot of those miles covered on the motorway at 2200 - 2800 rpm

The vehicle has been serviced at the right times using Mr T parts (in fact I do a 40K service at 20K)

I got an engine warning light on the way to work (35 miles A roads and Motorway) - this stayed on for the journey but had cleared when I restarted my car 8 hours later to come home. I took it to my local trusted garage who hooked it up and returned a P0400 error (My garage charged £15, Mr T wanted £96)

My questions are

1. Can a P0400 error ever by false?

2. Is having a few high revving sessions a real cure to clearing the valve?

3. How long should an EGR take before it gets to a stage where it needs cleaning / replacing?

4. Is cleaning a viable option or should the valve be replaced?

Any general feedback on the above would be appreciated

Thanks

[korat102]

1. Can a P0400 error ever by false?

2. Is having a few high revving sessions a real cure to clearing the valve?

3. How long should an EGR take before it gets to a stage where it needs cleaning / replacing?

4. Is cleaning a viable option or should the valve be replaced?

Any general feedback on the above would be appreciated

Thanks

This topic has been discussed to death all over the internet. The general consensus of opinion is that EGR is a typical political kneejerk reaction that looks good on paper but causes immense problems out in the real world...those problems are paid for by others so they don't give a damn. People started removing EGR equipment so the politicians, instead of admitting their mistake, simply made it illegal to attempt to undo their stupidity.

Anyway, getting back to your questions:

1. Doubtful, the ECU is reporting that the EGR control is not responding correctly. Could be blocked passages, a stuck valve, a problem with the wiring, etc.
2. Nope. The only way to reduce buildup of soot is to improve combustion, that really means better quality fuel (and maybe additives) and a nice clean air filter. In the long term though, EGR hardware will soot up, that's why it's such a stupid 'solution' to the emissions problem. If your engine is burning oil, that'll make the problem even worse.
3. How long's a piece of string? It depends on usage (lots of short runs without warming up properly will accelerate blockages), quality of fuel (better fuel has better additives to improve combustion and, thus, reduce unburned particles), whether or not your engine is burning oil (that'd add to the buildup very quickly).
4. You certainly can clean the EGR valve. It's just a bolted on piece of equipment. Remember to check the passages leading to and away from it as well. Take a look at http://www.toyotaownersclub.com/forums/topic/120290-egr-valve-cleaning/, amongst others.

Some people have had some success with fuel system cleaners like BG244. Tip it into the tank every so often to keep the injectors, pump, etc. nice and clean. Getting deposits off the injectors will improve combustion and, theoretically, reduce buildup of deposits. People who use it swear by the stuff, those who don't use it call it snake oil. It's pricey stuff so do some research and see if you think it's worthwhile...

Having said that, no additive will actually clean out a blocked EGR valve, so it's better to try to reduce buildup in the first place. At some stage, you will have to clean/replace it though - thank political blundering for that.

[stu_cole]

Thanks for the reply Phil

The car is driving fine, serviced at the right intervals (10K service last month), I do 40K services at 20K. Daily drive is 70 miles to work and back on A roads and the M1 with very little short runs or slow town driving. I have to accept the EGR will get sooted up but I am surprised with how quickly especially when I've due to mitigate the causes with proper care

Forgot to mention that the engine was replaced by Toyota (Free of Charge, known fault) last year due to a blown head gasket and I would have thought the EGR should have been checked cleaned and refitted as part of this process?

I have sent an e-mail to my local Mr T to ask the question above.

Thanks again

[stu_cole]

So, a month on and the car still has the intermittant light. Car is running fine with no rough running - been to speak to Mr T who now says could take a day or two to investigate at £65 per hour and with no certainty of finding the fault

As mentioned previously EGR & Suction Control Valve changed 2 years ago, Engine changed last year, Use good fuel, regularly serviced and my daily commute is 35 miles to work on good A roads and motorways

Attached is the log for the last three weeks or so, I can't see any link between temperature, weather, length of journey for when the light is on or off

Does anyone know the standard diagnostic times & procedures for a P0400 Error Code?

Check Engine Light Log.pdf

[mr_boks]

HI,

I have been having the same code reading for my 2006 Corolla Verso. Please see my post at:

http://www.toyotaownersclub.com/forums/topic/163531-intake-manifold-pressure-vs-atmospheric-pressure-error/

Also, please see Toyota Service Bulletin below

EG7043.pdf

[stu_cole]

I've also discovered something odd;

When I brim the fuel tag the engine warning light will go off for approx 120 miles and then come back on again

I'm unsure of this relates to a P0400 error