AHHH.. PO401 32 hours before carlisle departure

Robert-sl2 · 05-12-2004, 11:41 PM

Does this mean my EGR is completely toast, stuck open, closed?!?! It comes on just as the car gets upto temp, which is when the valve is supposed to close, right? Any ideas. I am gonna swap in my old EGR, I got a new one from joey about a month or 2 back (which is the one throwing the code now). Anything else I shoudl check?

On my way home for lunch it came on just as the car got to temp. stopped, had the code pulled then cleared. came home, car sat for an hour or so, drove back to school, no code. car sat for 4 hours, drove home and it came back just as the car got back upto temp.

Ideas?

**Ssicarman** · 05-13-2004, 01:54 AM

have a read on this. From 98 but should be the same for yours.

DTC P0401

The linear EGR system consists of a linear EGR valve, the PCM, and its associated wiring. The PCM directly controls the ground for the EGR valve when certain conditions have been met. Voltage is supplied by the UHJB to the EGR valve when the ignition is turned ON. When the PCM grounds the valve, a diagnostic feedback signal can determine if the valve had actually moved. Since the correct feedback voltage is possible, but the passage has restricted flow, DTC P0401 was implemented.

Conditions for Setting the DTC
EGR flow restrictions are diagnosed during a deceleration. The EGR valve is commanded closed during a normal deceleration. To run the DTC P0401 test, the valve is opened during deceleration and a change in MAP is expected. If the change in MAP is below a threshold, it indicates flow is restricted.

Important
The EGR flow insufficient test is checked once per ignition cycle during deceleration.

DTC P0401 will set if a calculated value compared to an engine speed vs barometric pressure determines there is a restriction in EGR flow when:

Engine speed is between 1,350-2,000 RPM.
The VSS is greater than 48 km/h (30 mph).
The throttle is closed.
The engine coolant temperature is greater than 70Â°C (150Â°F).
The vehicle is in top gear.
No EGR pintle, TP sensor, MAP, VSS, IAT, ECT, or IAC DTCs have been set.
Diagnostic Aids
The scan tool can read the number of deceleration tests that have been performed since the DTCs were cleared. The scan tool also displays the EGR decel average value as well as the FAIL threshold when the DTC will set. The average must be greater than the threshold to set DTC P0401.

Carbon build-up around the EGR pintle valve bore opening may restrict exhaust gas flow. Build-up of carbon in the EGR passages will result in DTC P0401.
Diagnose the other DTCs listed under parameters, especially a MAP sensor DTC, before diagnosing DTC P0401.

Davage · 05-13-2004, 02:39 AM

Once again, you are fantastibar, Ss! Great info, greatly appreciated. I'm on my third EGR valve when Joey's engine gets here (it's coming along for the ride w/engine.). Mine toasted at 60k km, and again at 120k. I think it was my seals letting all that extra oil I have to put in the Satty into the combustion chamber (not sure, right Ssic?). That's what I can see from MY factory engine

, but EGR is a long km/mile maintenance item anyhow, correct? I've seen tell of removing, but I design buildings, and if you removed something I designed, the whole freakin deal might come down...well...it might. So I'm leaving one connected to my car. Beside's, if you leave a bad one on, you have stalling issues, starting issues, SES issues, etc. Just personal experience.