EGR replaced, now DTC: P040200 & P046C00 with low power

A

Aeroflyer

New Member
Hello to you all!
I am so sorry to jump in here with a problem, but it's looking to me that this is the best place to ask.
I replaced the EGR assy. on my friends T6 CXHA engine. Unfortunately I didn't have the function on my tester to "Code" it in, I don't have VCDS (but would like to if anyone knows of a link ;-) )
Would this be the cause of the DTC's P040200 & P046C00 being set? And therefore would coding it as having had a replacement EGR assy. fix the issue?
My friend knows of a garage that should have the VCDS or similar so he will take it there anyway. I am just asking here if anyone has had the same issue. Or am I barking up the wrong tree??

Thanks in advance
 
Aeroflyer said:
I replaced the EGR assy. on my friends T6 CXHA engine. Unfortunately I didn't have the function on my tester to "Code" it in,
Click to expand...
Workshop manual does not mention any need for adaptation.

Aeroflyer said:
P046C00
Click to expand...
Implausible Signal. The code indicates that EGR valve doesn't do what ECU wants it to do.

Aeroflyer said:
P040200
Click to expand...
Excessive flow. Possibly is just a consequence of e.g. EGR valve not closing properly thus too much exhaust gas entering back into engine intake.
Is the replacement OEM VW part?
Please verify the EGR valve operation, e.g. as below

C

Thread 'EGR Valve Self Test Procedure (IDE00242)- P046C?'

So, I've been getting the all too common P046C fault code along with P2457 (Insufficient EGR Cooling Performance). Neither alone will flag a check engine light but combined they sometimes seem to. To try to figure out what is going on, I ran an EGR Flow test on VCDS using instruction from @mmi on this rather excellent page:

www.t6forum.com

[T6_measured] 01-Engine - Built-in test for EGR

T6.1 DNAA engine The test runs differently than on T6 CXxx engines - less cycles. Instructions of post #1 still apply.
www.t6forum.com www.t6forum.com

I didn't spot much relating to the EGR funtion but the EGR valve reading itself was interesting. Basically, it didn't appear to be fully closing.

My confidence with...
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J

Thread 'Egr problem'

Hello
I have just changed my egr valve (about 1000km since) and since that my glow plug lamp and engine lamp keeps flashing 1-3 times a day. What can be the problem?

Code: 
Chassis Type: 7H-VN75 (7E0)
Scan: 01 02 03 04 05 08 09 13 15 17 18 19 22 25 5F 61 69 6E 8C BD
          C6 0B

VIN: WV1ZZZ7HZGH086356   Mileage: 211800km-131606miles

01-Engine -- Status: Malfunction 0010
02-Auto Trans -- Status: OK 0000
03-ABS Brakes -- Status: OK 0000
04-Steering Angle -- Status: OK 0000
05-Acc/Start Auth. -- Status: Cannot be reached 1100
08-Auto HVAC -- Status: OK 0000
09-Cent. Elect. -- Status...

Aeroflyer said:
I don't have VCDS (but would like to if anyone knows of a link ;-) )
Click to expand...
 
Hello MMI,
Thanks very much for your answer.
I read through those other posts prior to posting, but I can't run any tests right now as the van is about 20 miles away.
The EGR is not an OEM part sadly.
When road-testing the van I had the EGR position "Actual value" and "reference value" displayed as well as the deviation. The Actual value varied mostly in the range of 5 to 9% with the occasional jump momentarily to 45% and once or twice higher, hitting 100% only once during the 25 mile drive. The reference value was oddly (I thought) much lower usually around 2 % when the actual value was at 8.8% with the deviation saying 95% or more most of the time. At one point both values were identical, which is what I would have expected to see but sadly this was rarely observed.
So I guess it looks like a dodgy new part. Thoughts?
I was hoping it was just because it needed coding to the car but you said it does not say that it's needed??
It's a 2017 model year if that makes any difference at all.
 
Aeroflyer said:
When road-testing the van I had the EGR position "Actual value" and "reference value" displayed as well as the deviation. The Actual value varied mostly in the range of 5 to 9% with the occasional jump momentarily to 45% and once or twice higher, hitting 100% only once during the 25 mile drive. The reference value was oddly (I thought) much lower usually around 2 % when the actual value was at 8.8% with the deviation saying 95% or more most of the time. At one point both values were identical, which is what I would have expected to see but sadly this was rarely observed.
Click to expand...
Might be just your diagnostic tool but the values are not exactly what I'm expecting - typically showing -20...-40% also for the commanded value. Possibly the monitored values were just generic OBD channels which don't show e.g. EGR cooler bypass mode (=negative values).
Anyways, I think the bottom line is that ECU doesn't like what it sees.

Aeroflyer said:
So I guess it looks like a dodgy new part. Thoughts?
Click to expand...
Well, at least not fully compatible. Quite well known challenge with third party parts on modern engines.

Aeroflyer said:
I was hoping it was just because it needed coding to the car but you said it does not say that it's needed??
It's a 2017 model year if that makes any difference at all.
Click to expand...
Based just on the workshop manual (missing) statement for this specific engine for the model year.
For items needing coding, calibration, adaption etc. workshop manual has a statement and instructions.

Page 341 -
Installing

Install in reverse order of removal, observing the following:
– Renew nuts ⇒ Item 13 (page 336) and studs
⇒ Item 5 (page 335) with bolts following removal ⇒ Electronic Parts Catalogue (ETKA) .
– Renew exhaust gas recirculation pipes following removal.
– Renew gaskets after each removal.
Click to expand...
4-cylinder common rail engine CXEB CXFA CXGA CXGB CXHA CXGC CXHB Loz

4-cylinder common rail engine CXEB CXFA CXGA CXGB CXHA CXGC CXHB

CXEB CXFA CXGA CXGB CXHA CXGC CXHB
  • Loz
  • cxeb engine cxfa engine cxga engine cxgb engine cxgc engine cxha engine cxhb engine manual
  • VW Manuals
 
Thanks again for your answers.
I agree that it could just be Generic OBD channels, as I never saw any go into the minus range.
I will go again to see if the valve is actually moving when commanded.
The reason for the replacement was due to coolant leaking from the cooler into the gas chamber and subsequently being ingested to the engine (was slow leak).
If it comes to it I will just have to remove the damn thing and swap the EGR valves (put the original Pierburg valve onto the new cooler).

I don't seem able to download the workshop manual that you linked, is that only an option for VIP Members?
 
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