1994 850T EGR code 241 sys flow malfunction

cBobs94850T · Post by **cBobs94850T** » 18 Apr 2014, 08:42

Resently started getting this code pop up. Is this indicative of a failed EGR or more likly a vacuum issue.
I removed the EGR (PIA) for cleanning a couple of years ago.

Post by **Ozark Lee** » 18 Apr 2014, 19:13

Here is the book procedure

2-4-1 (EGR Flow Incorrect)

1 ) EGR temperature sensor signal should change when signal
from ECU is sent to vacuum controller. If signal does not change, ECU
registers a fault and sets code. Possible faults include:
* Break in signal lead.
* No voltage at EGR controller.
* Faulty EGR controller.
* Poor vacuum supply to EGR valve (White vacuum hose).
* Faulty Yellow vacuum hose.
* EGR valve does not open.

2 ) To check operation of EGR vacuum controller, start and run
engine so it reaches normal operating temperature. Put hand on EGR
controller and increase engine speed several times over 2000 RPM. If
EGR controller produces a ticking sound, go to next step. If EGR
controller is not ticking, go to step 9) and check voltage supply to
EGR controller.

3 ) Ensure engine is still running. Carefully disconnect White
vacuum hose from EGR controller and check for vacuum. If vacuum is not
present, check White vacuum hose between controller and intake
manifold. If vacuum is present, go to next step and check vacuum from
EGR controller.

4 ) Turn ignition off. Reconnect White vacuum hose to EGR
controller. Carefully disconnect Yellow vacuum hose from EGR
controller. Connect vacuum gauge to EGR controller. Start engine.
Increase engine speed repeatedly. If gauge pointer moves rapidly,
verifying EGR controller is passing vacuum, go to step 6) and check
EGR valve. If gauge does not move rapidly, go to next step.

5 ) Turn ignition off. Carefully disconnect Yellow vacuum hose
at both ends. Check Yellow vacuum hose for blockage. If hose is okay,
repeat test using new EGR controller. If hose is blocked, repeat test
using new vacuum hose.

6 ) To check EGR valve, turn ignition off. Reconnect Yellow
vacuum hose to EGR valve. Connect vacuum pump to Yellow vacuum hose at
EGR controller. Start engine. Increase vacuum to 9 in. Hg. (30 kPa).
Ensure EGR valve retains vacuum (engine will run rough).

7 ) If engine runs rough when vacuum pump shows vacuum but
vacuum pump loses vacuum, check Yellow vacuum hose for leakage. If
hose is okay, retest using new EGR valve. Clear codes. If engine idles
evenly when vacuum pump shows vacuum and vacuum pump maintains vacuum,
ensure EGR pipe is not blocked. If pipe is not blocked, repeat test
using new EGR valve. Clear codes.

8 ) If engine idles rough when vacuum pump shows vacuum and
vacuum pump maintains vacuum, fault is intermittent. Check vacuum
controller connector. If connector is okay, check Green/Brown wire
between EGR controller terminal No. 1 and ignition ECU terminal No. 27
for intermittent short to voltage or ground.

9 ) If EGR controller was not ticking in step 2), check
voltage at EGR controller. Turn ignition on. Disconnect EGR controller
connector. Connect voltmeter between EGR controller connector terminal
No. 2 and ground. See Fig. 8. If voltmeter indicates battery voltage,
go to next step and check signal lead. If no voltage is present, check
for open circuit in Green wire between EGR controller terminal No. 2
and main relay terminal No. 3. Clear codes.
Fig. 8: Identifying EGR Controller Connector Terminals
Courtesy of Volvo Cars of North America.

10 ) To check signal lead, turn ignition on. Disconnect EGR
controller connector. Connect voltmeter between wiring side of EGR
controller terminals No. 1 and 2. See Fig. 8. If battery voltage is
not present, check for open circuit or short to voltage in Green/Brown
wire between EGR controller terminal No. 1 and ignition ECU terminal
No. 27. Clear codes. If battery voltage is present, go to next step.
11) To check EGR controller resistance, turn ignition off.

Disconnect EGR controller connector. Connect an ohmmeter between EGR
controller terminals. See Fig. 8. If ohmmeter shows 75-95 ohms at 68 F
(20 degrees C), check EGR controller connections for oxidation. Clear codes.
If ohmmeter does not show 75-95 ohms at 68 degrees F (20 degrees C), repeat test using
new EGR controller. Clear codes.

...Lee

cBobs94850T · Post by **cBobs94850T** » 21 Apr 2014, 16:17

Thanks you very much Lee

Sorry it took me so long to get back to you, have been under the weather

sullihood · Post by **sullihood** » 09 Mar 2015, 20:14

is this procedure the same for a 94 940T? I also have a 2-4-1 code on A6. Thank you in advance.

Post by **Ozark Lee** » 09 Mar 2015, 20:27

I'm not sure, the wire colors may be different but I think the basics are the same.

The usual problem with the EGR low flow code is the hole in the intake manifold from the valve EGR valve being clogged up. We have had members that cleared the hole on an 850 by removing the throttle body but it is easier to clean it up with the intake manifold removed. I had the same code with my son's 850 and the carbon that was caked in the hole was like concrete.

I know nothing about the 940 EGR setup but if the EGR valve bolts to the intake manifold then the same things likely apply.

...Lee

sullihood · Post by **sullihood** » 09 Mar 2015, 22:16

Lee,

Thank you for the input. The engines are very different so I am not sure but I don't think that the procedure will work on the 940T. I plan to dig into this tomorrow evening. The EGR sure is in a tough spot to get to.
Thanks,
John