Engine check light on - EGR valve

[Almo]

Hi Guys, I haven't been on here for some time as the vans been going good until recently when the check engine light came on. I got my mate who's an auto electrician to scan it and on the screen it said EXHAUST GAS RETICULATION 'A' CONTROL CIRCUIT HIGH.

Anyone got any ideas what this means? Looking at the EGR valve it looks like a previous owner has put a blanking plate in where the exhaust gases enter the valve. Which leads me to think they must have done something else as well to fool the ECM to think that the EGR valve was operating as per normal to prevent the CEL from coming on?

This is not my area of expertise so any help really appreciated. BTW the van is running as per normal. 

Cheers.

[Almo]

Back again... So today I pulled the EGR assembly apart and all is well and clean inside as you would expect due to being blanked off. The electric motor spindle and toothed gear turn freely and smoothly and so does the valve  actuator (correct name?)that the motor spindle slips over. So mechanically all seems well so now I'm suspecting its electrical. 

I started the engine when i had it apart (its been blanked off remember) and got my buddy to watch the EGR motor spindle and it didnt move once, same when I gave it some revs. So is that a fair test to prove that its not working? I have a multi meter but I'm not sure how to test the connector lead that goes to the motor for power? Or is there a resistance value I should look for across the terminals of the motors plug? There's nothing in my Haynes manual on how to test the EGR.

All I'm trying to achieve  here is to get the Check Engine Light off. 

Thanks for any advice offered.

[Almo]

9 hours ago, LostnTransit said:

I'm not an engine expert. I can do a few random things like clean the airflow sensor with mass airflow cleaner etc.. I leave the major stuff to the performance shop. But it seems that all one needs to do is to have someone scan your system for the error code, then remove it. 

Yes I did get my auto electrician friend to scan it. It came up: P0490 EXHAUST GAS RETICULATION 'A' CONTROL CIRCUIT HIGH. I must ask him if it is possible for him to remove/clear the alert using the machine he has. I'm guessing though that until I sort the electrical issue it wont be able to be removed.

Edited September 30, 2022 by Almo

[lowspeedpursuit]

Without having it in front of me, I would say your assessment that the stepper motor/whatever electrical controls failed is likely correct. P0490 is consistent with that failure.

 

This isn't TC-specific, but generally with EGR the computer wants two things: to reliably actuate the valve, and to observe the resulting changes in airflow. The first one is easy: you just leave the valve/solenoid/whatever plugged in electrically, even though you've blocked off the intake/exhaust ports. The second one is generally more difficult, but clearly if your CEL was off before then either the TC doesn't check that, it's easy to bypass, or the PO figured something out.

 

I can't give you the EGR diagnostic procedure because it's in some stupid bespoke "Emissions Diagnosis" manual, but for the six-pin stepper motor, two wires of the same color (US 2010 is Green) are hot through the PCM power relay and Fuse 26, and the other four wires run to the PCM. Inside the motor are four coils, so each of the pins to the powered wires should be continuous with two of the PCM pins. I'm not sure how things work down there, but I can get the valve+motor assembly for $41 shipped, so it's also not absurdly expensive to just fire the parts cannon at this one.

 

[Almo]

Hey great, thanks very much for this info. My auto electrician friend will be able to decipher all of what you said about the six terminals and which does what. 

Yes I was thinking same about just purchasing a new stepper motor (I know the correct name now!) but I hadn't looked into yet. I'll have a look on UK e-bay as that's where I get most of my bits from. Luckily it will be a small package as freight has gone nuts since covid. Thanks again for your help, I'll update this thread as I progress.

[Almo]

Back again guys.... So I ended up replacing the stepper motor then got my friend to clear the historical error code. The light stayed off for about the first 3 trips around town then came back on again. It's been back on pretty much all the time since apart from one morning I started it up and it was off but came on within the first 10 miles. Today I got my friend to scan it again and its the same code as before - P0490 EXHAUST GAS RETICULATION 'A' CONTROL CIRCUIT HIGH. 

Does anyone know what this code actually means? What's the 'A' control circuit?

TIA.

[lowspeedpursuit]

So this isn't terribly helpful, but the only way to get a more accurate diagnosis (short of finding someone with this exact problem) is with the Emissions manual I don't have. Whether that means taking it to a shop, or buying that manual or access to its information yourself, or trying to get in contact with the previous owner to get more information about exactly how he bypassed the CEL during the EGR delete.

 

Without the manual, all we know is that the PCM doesn't like the voltage it's seeing from the EGR system. Whether that's the fault of the EGR, the PCM, the wiring between them, or some other part of the system I'm not familiar with is anyone's guess. On a quick google, you've got this guy saying he had a bad EGR valve, but then his new aftermarket EGR valve kept throwing the CEL because even in working condition it produced out-of-spec voltages. So replacing the EGR doesn't rule out that possibility, and the only thing you can really do on your own at this point without throwing more money at it is inspect the wiring.

 

Even if Forscan (or other OBDII live data) can show you EGR voltages, unless they're completely insane they won't mean much without the manual. Is it possible for your tech friend to help you come up with one?

[Almo]

On 1/28/2023 at 6:20 AM, lowspeedpursuit said:

So this isn't terribly helpful, but the only way to get a more accurate diagnosis (short of finding someone with this exact problem) is with the Emissions manual I don't have. Whether that means taking it to a shop, or buying that manual or access to its information yourself, or trying to get in contact with the previous owner to get more information about exactly how he bypassed the CEL during the EGR delete.

 

Without the manual, all we know is that the PCM doesn't like the voltage it's seeing from the EGR system. Whether that's the fault of the EGR, the PCM, the wiring between them, or some other part of the system I'm not familiar with is anyone's guess. On a quick google, you've got this guy saying he had a bad EGR valve, but then his new aftermarket EGR valve kept throwing the CEL because even in working condition it produced out-of-spec voltages. So replacing the EGR doesn't rule out that possibility, and the only thing you can really do on your own at this point without throwing more money at it is inspect the wiring.

 

Even if Forscan (or other OBDII live data) can show you EGR voltages, unless they're completely insane they won't mean much without the manual. Is it possible for your tech friend to help you come up with one?

 

Thanks for your reply and sorry bout slow response. I'm understanding what your saying and I'll ask my friend if can access that info. I'll have a closer look at the wiring too. The previous owner wont communicate with me any longer, I asked him too many questions when I bought the van initially lol! I'm going to pull the blanking plate out and see if it has a hole in it as a matter of interest and whether its blocked over partially or fully with soot. 

Edited January 31, 2023 by Almo