v70 2.4D Euro4 06 163bhp DTC P0489 (P0403 now cleared)
 

Hi,

Code definitions
P0489 - EGR A Control Circuit Low
P0403 - EGR A Control Circuit/Open

Here is what has happened...
First really cold morning I went to drive car and instantly there was no power, just a slow linear rev increase with no boost. It can drive up to any speed but hills require down gearing and fuel ecomony realitively normal. Engine Service Required Light on dashboard.
By the time I was coming home from town the power came back again and car was normal but light was still on. For 2 days the light was on but car had power and on 3rd day light went out. Then next overly cold morning the light came on and the power was gone again. This has not changed since. Pity as I need to tow a trailer and this ain't happening right now.

I went to local repair shop to check codes and he just said about EGR needing investigated and code comes back as soon as it is cleared and so I went home thinking of the mounting list of things wrong with this car needing repaired!!!!!.
Having recently seen something online about the crud that gathers in the EGR and associated pipes up into the inlet manifold I thought first thing I will do is clean that out and sure enough the EGR and pipe to the left that attaches to top of manifold was full of crud. I did not remove the EGR to do this, took out air box to the right and the pipe to the left then just scraped out the inside of the EGR and the removed pipe, and washed out with carb cleaner. The pin in the middle of the EGR was well cleared of crud especially around both ends of pin, as clean as one could make it.
Put it all back together and problem still was there. Was it because the codes not cleared, so I bought a reader to clear myself rather than go to garage again.
On first reading I got 2 codes as above, I cleared them and instantly one code came back the other has not returned. The code coming back was the P0489.

Would the above suggest that due to crud the pin/something remained open perhaps causing P0403 and due to stickiness the 'EGR Valve Stepper Motor' has failed giving P0489, I've cleaned inside the EGR, the pin is no longer open and the EGR Valve Stepper Motor is tits up?
I read that here https://www.partsforvolvosonline.com...oducts_id=8461

If I was to replace this then I suppose it woud fail again if the EGR pin was having issues despite my cleaning of it, so rather than buy a new stepper motor getting a second hand egr with stepper motor on it is best and cheaper than a new stepper motor?
I can only assume the collant part of the EGR does not need replaced and has no bearing on this error. I will also say that the Throttle Flap to the right of the EGR was taken off and cleaned and the flap can be manually moved and flips back when finger is removed.

These I am not sure about, is this easy, is this likely to be also a problem associated above and the above it fine its these that could be the reason?
- Test EGR control solenoid connector for a voltage and ground signal
- Test for a voltage signal between the ECM and EGR electrical connector

I don't think its about vacuum pressure and valve opening as the core problem seems to be the Control Circuit Low, flagged as soon as the ingnition is on.

Current existing issues, swirl flap plastic end is broken off so (the missing!) bar connecting to actuator cannot be refitted and have checked the Turbo Control Valve and not getting vacuum from the pipes going to the engine mounts. These I believe have only minor effects on performance and should have no direct effect on EGR operation.

Unless there are any smart ideas out there for a fix, I assume its an EGR/stepper motor replacement? (but could be the power to the EGR that is the issue?)
Do I really need to check the power to the EGR first before wasting time and money replacing (ebay!) however if it had been that failed surely that would have been failure complete and not come back for a few days before failing again. That is why I a lean towards sticking EGR, stepper motor struggled to actuate, came back, then under pressure from crud stepper gone?

Cancel...………………….

Or having read more about P0403 - EGR A Control Circuit/Open the code I cleared - https://www.yourmechanic.com/article...by-jay-safford

Maybe this is the original problem that then leads to the EGR being turned off, therefore creating the P0489 code. After clearing the codes and the EGR remaining in the off position it therefore instantly flags in the P0489 code there is no way to get P0403 to show again because the EGR is rendered in the off state. If you forced the EGR to work it would again see the open circuit again? So its a EGR vacuum solenoid that needs replaced maybe???

OKay further info -

Today I tested the Turbo Control vacuum just to make sure my loss of power was not related to that and it was just the EGR at fault. I crimped the vacuum line to the engine mounts to create the vacuum *and engine noise patter with oil cap removed went down as should do when vacuum is present) and I still had the power loss. So back to the EGR.

After doing this I got the P0403 error back again as well as having the P0489, so I looked into the solenoid error on EGR (as perhaps that is leading to the other error) and I found the cable chaffed a bit (that attachs to the EGR Solenoid Valve), through the outer layer and some of the copper strands broken but still intact.
See pictures in post below
Another weird thing is in the other picture of where the power lead attaches too has a + sign on the top and I would assume the +positive power cable is meant to be at that side of the connector, however on using the voltage meter I found the +pos to be the other side! (I have not had these faults before and this has not changed so must be fine, just confusing that + sign on the housing does not refer to the +pos on the power lead)

Anyway with car running I got 10.98V and when car off with ignition on 8.48V, as soon as I tested and turned car off, it trickled down to 8.48 from the 10.98, it was not instant.
Should this be the full 12V? Is the damaged wire causing voltage loss, I'd have thought even if the wire was half the thickness it would still carry the full 12V so a few strands gone of the copper should not lower the Voltage?

Am I right that the Valve provides vacuum to the solenoid somewhere else on the EGR? I see solenoids can be bought but are they actually part of the EGR itself, so if I got the EGR with stepper motor on it (not needing the cooler) that will have the solenoid in it?

Pictures now attached

Did a data stream and MAF at idle is 15g/s.

Perhaps a little high? but certainly better than low or nothing, so MAF does not look to be a factor in causing any of the EGR faults.

Just ruling something else out.

Fascinating reading. Did you ever get to the bottom of this?

Fly crab fat. :tongwink: