Folks,

My son called from college. He has a check engine light with a P0400 code on his 95 Turbo. I know it is most likely the EGR valve/port is clogged. Now for the twist. Since he is at college, it will be a bit before I get to help him clean it out. So, how long do you think he could drive it with the EGR malfunctioning? Also, I really would like if someone could point me to a link/write-up, etc on pulling and cleaning the EGR WITHOUT pulling the manifold.

Many thanks in advance for any help.

Glenn

 

P0400 = DTC 2-4-1

If the EGR valve is stuck shut, it won't hurt anything at all (except the environment slightly..).

If EGR valve is sticking open, that's another story; makes for a big vac leak!

From the 95 Turbo 850 Manual
===========================
Code 2-4-1 (EGR System, Flow Malfunction)
1) Turn ignition on. Use Volvo Scan Tool (998-8686) parameter
Diagnostic Test Mode No. 3 and check EGR controller functions. If EGR
controller operates, go to next step. If EGR controller does not
operate, go to step 7).
2) Turn ignition off. Disconnect wire at EGR controller
connector terminal No. 2. Connect a jumper wire between EGR controller
connector terminal No. 2 and ground. Start engine and run at idle. If
engine runs unevenly at idle, fault is intermittent. Go to step 11).
If engine does not run unevenly at idle, go to next step.
3) Turn ignition off. Carefully remove White hose from EGR
controller. Connect vacuum gauge to White hose. Start and run engine
at idle. If vacuum gauge gives any reading, go to next step. If vacuum
gauge does not give a reading, ensure White vacuum hose and connection
to intake manifold are not blocked.
4) Start and run engine at idle. Connect White hose to EGR
controller. Carefully disconnect Yellow hose from EGR controller.
Connect a vacuum gauge to EGR controller connector. Connect loose wire
on EGR controller to ground so as to open EGR controller. If vacuum
gauge gives any reading, go to next step. If vacuum gauge does not
give a reading, retest using new EGR controller.
5) Turn ignition off. Carefully disconnect Yellow hose from
EGR valve. Check Yellow hose for leaks or obstruction. Repair as
necessary. If hose is okay, go to next step.
6) Turn ignition off. Connect Yellow hose to EGR valve.
Connect vacuum pump to Yellow hose at EGR controller. Start engine and
run at idle. Pump vacuum to maximum of 4.35 psi (30 kPa). Check that
EGR valve retains vacuum. Engine should run unevenly when vacuum pump
shows negative pressure. If engine runs evenly when vacuum pump shows
negative pressure but vacuum pump loses vacuum, test using new EGR
valve. If engine runs smoothly at idle when vacuum pump shows negative
pressure and vacuum pump retains vacuum, check if EGR pipe is clogged.
Repair as necessary. If EGR pipe is okay, retest using new EGR valve.
7) If EGR controller does not operate, turn ignition off.
Disconnect EGR controller connector. Turn ignition on. Connect
voltmeter between EGR controller connector terminal No. 1 and ground.
If battery voltage is present, go to next step. If battery voltage is
not present, check wiring between EGR controller connector terminal
No. 1 and main relay connector terminal No. 3 for an open circuit.
8) Turn ignition off. Disconnect EGR controller connector.
Disconnect ECM connector. Connect breakout box to ECM connector.
Reconnect ECM. Connect ohmmeter between breakout box pin No. 40 and
EGR controller connector terminal No. 2. If ohmmeter reads zero ohms,
go to next step. If ohmmeter does not read zero ohms, check wiring
between EGR controller connection terminal No. 2 and breakout box pin
No. 40 for an open circuit.
9) Turn ignition on. Disconnect EGR connector. Connect
voltmeter between breakout box pins No. 40 and 42. If voltmeter reads
less than one volt, go to next step. If voltmeter does not read less
than one volt, check wiring between EGR controller connector terminal
No. 2 and breakout box pin No. 40 for a short circuit to voltage.
10) Turn ignition off. Ensure EGR connector is connected.
Turn ignition on. Use Volvo Scan Tool (998-8686) to check if EGR
controller functions. If EGR controller functions, code was caused by
poor contact in control module and/or EGR controller connector. Repair
as necessary. If EGR controller does not function, retest using new
EGR controller.
11) If fault is intermittent, check EGR controller connection
and ECM connectors for signs of loose connection and contact
resistance. Check wiring between EGR controller connector terminal No.
2 and ECM connector terminal No. 40 for an intermittent open circuit.
Also check wiring between EGR controller connector terminal No. 1 and
main relay connector terminal No. 3 for an intermittent open circuit.