Pesky C5 2004 Antipollution Fault displayed

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BSC
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Pesky C5 2004 Antipollution Fault displayed

Post by BSC »

I installed an EGR blanking plate to fix the stuttering while cruising problem (which it did) and I just got back from a 565 mile round trip from Falmouth to Heathrow and back. No issue until I stopped the car at Heathrow for 5 mins to drop my wife off and when I restarted the car, the Antipollution Fault appeared! Why's that? The car is running as before, but why would the fault be displayed after 270 odd miles including a couple of stops. After the fault display appeared, the car ran as before with no issues. I would have expected the error to have appeared after a few miles rather than 270!

I know I can temporarily remove the code, but is an ECU remap the only way to stop it coming back again?

Cheers
David
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Re: Pesky C5 2004 Antipollution Fault displayed

Post by Hell Razor5543 »

It may NOT be the EGR at fault. I have seen certain temperature errors causing this. Next time I get an AP Error I will check it on my Lexia.
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Re: Pesky C5 2004 Antipollution Fault displayed

Post by citroenxm »

The anti pollution Fault message is a Generic Code for ANYTHING to do with fuel and exhaust! It can come on for turbo issues, IE over boosting, Lack of fuel pressure, Blocking exhaust, faulty EGRs faulty EGR/Turbo wastegate electro vaccum solinoids and so on!

So it could have come up for something else! Without reading with the lexia you wont know what preciesly the issue is
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Re: Pesky C5 2004 Antipollution Fault displayed

Post by BSC »

Thanks. I'll hook up the Lexia and see what pops up. I just assumed it was the EGR because that's what I'd changed.

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Re: Pesky C5 2004 Antipollution Fault displayed

Post by BSC »

Here are the codes I got, P0402 & P0400 - both are EGR related. I don't believe there's an option in Lexia to switch off the EGR, so what's the solution? Any help appreciated.

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Re: Pesky C5 2004 Antipollution Fault displayed

Post by citroenxm »

P0402 is excessive egr circulation .. either a sticky valve thats open which it cant be you have removed it .. OR the egr valve sensor faulty.. more likely if you still have it on the car..... the only way to remove egr from the ecu is to send it off to a ecu speicalist. The egr shouldnt really be removed by law in the uk thats why theres no option to switch it off in the lexia and only an ecu specialist can do it...
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Re: Pesky C5 2004 Antipollution Fault displayed

Post by Lighty »

We can delete specific Ecu codes, but you will really need an egr delete. On some engines, particularly the 1.6 hdi, you still need an electrically sound egr valve, as the engine Ecu needs relevant information from it to operate correctly, so things like esp/asr continue to work correctly.
Just blanking it off physically will not cure your cars issues completely in most cases.
You have two options
Fit a new valve
Have it mapped out correctly
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Re: Pesky C5 2004 Antipollution Fault displayed

Post by BSC »

I removed the EGR and found that when I poured fluid into it, it leaked. I bought a replacement and there were no leaks. I assumed that the leaking was the problem, but no. I got exactly the same problem of stuttering and smelly fumes. The blanking plate did the trick. I would rather keep a functioning EGR and eliminate codes, but I don't know where else to look?

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Re: Pesky C5 2004 Antipollution Fault displayed

Post by cachaciero »

Which engine are we considering here ?
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Re: Pesky C5 2004 Antipollution Fault displayed

Post by BSC »

cachaciero wrote:Which engine are we considering here ?
Sorry, should have mentioned it before - 2.0HDi

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Re: Pesky C5 2004 Antipollution Fault displayed

Post by RichardW »

Presumably this is an 8V 110 BHP engine? In which case the EGR is dumb - as it is vac operated, and there is no direct flow sensor. I would suspect that the MAF has gone west. What does Lexia give as the air flow readings at idle? Does it increase nicely as the engine is revved?
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Re: Pesky C5 2004 Antipollution Fault displayed

Post by BSC »

It is the 8V engine. I changed the MAF to correct a previous performance problem. I'll hook it up to Lexia and check the air flow to see what's happening.
Thanks
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Re: Pesky C5 2004 Antipollution Fault displayed

Post by cachaciero »

As RichardW points out the EGR on this engine is dumb, the system assumes that the valve position corresponds to the vacuum applied. The control valve (electro-valve) is electrically controlled with a PWM signal the output vacuum being proportional to the ration of the Pulses. Checking of the control valve is one of the first things to do if it is lacking vacuum or sticky that will of course reflect into the EGR valve. Vacuum is critical to much off (all of? ) the engine control so I would strongly suggest checking the vacuum using a vac gauge at key points, if there are leaks in the system it can cause all sorts of strangeness depending on where the leak is. It is in my mind that the Turbo dump valve is also vac controlled same thing if the vac is fluctuating then the dump valve could "chatter" giving you similar effects and of course that also feeds into EGR. If this was an electrical system then one would be looking for fluctuating power to the valve, in this case the power is vacuum.
Might be worth monitoring the Turbo pressure when you have the problem. And.......has already been suggested there is the MAF, however the time constants around the MAF are quite long, in fact the time constant of any of the control loops going through the ECU are quite long so I would expect that anything wrong with one of those loops would feel more like a lower frequency surge rather than a stutter, stutter does suggest to me more like like an intermittent valve operation.the operation of all the valves can be exercised using the Lexia.
While the system does not measure EGR pressure or flow as such I believe the ECU can and does detect problems on the electrovalve solenoids i.e to little or too much current in the coil but I don't know what error codes it would flag for such a failure.
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Re: Pesky C5 2004 Antipollution Fault displayed

Post by BSC »

cachaciero wrote:As RichardW points out the EGR on this engine is dumb, the system assumes that the valve position corresponds to the vacuum applied. The control valve (electro-valve) is electrically controlled with a PWM signal the output vacuum being proportional to the ration of the Pulses. Checking of the control valve is one of the first things to do if it is lacking vacuum or sticky that will of course reflect into the EGR valve. Vacuum is critical to much off (all of? ) the engine control so I would strongly suggest checking the vacuum using a vac gauge at key points, if there are leaks in the system it can cause all sorts of strangeness depending on where the leak is. It is in my mind that the Turbo dump valve is also vac controlled same thing if the vac is fluctuating then the dump valve could "chatter" giving you similar effects and of course that also feeds into EGR. If this was an electrical system then one would be looking for fluctuating power to the valve, in this case the power is vacuum.
Might be worth monitoring the Turbo pressure when you have the problem. And.......has already been suggested there is the MAF, however the time constants around the MAF are quite long, in fact the time constant of any of the control loops going through the ECU are quite long so I would expect that anything wrong with one of those loops would feel more like a lower frequency surge rather than a stutter, stutter does suggest to me more like like an intermittent valve operation.the operation of all the valves can be exercised using the Lexia.
While the system does not measure EGR pressure or flow as such I believe the ECU can and does detect problems on the electrovalve solenoids i.e to little or too much current in the coil but I don't know what error codes it would flag for such a failure.

Thanks for that! I'll go through the suggestions and see what emerges.

Cheers
David
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