1996 Subaru Impreza Check Engine Light

TIGER-GOAT

MEMBER
1996 SUBARU IMPREZA
4 CYL
AWD
AUTOMATIC
16,900 MILES

Hello all, I have a recently acquired 96 Impreza wagon with the 2.2L 4 cylinder engine. The check engine light came on a few weeks ago, so I checked the code and it came back P0400 EGR which I was told was the Exhaust Gas Regulator (I think I am remembering that right) So I order one and replaced it easily enough. But the light is back on, with the same code, I was told this time that it might be a vacuum leak from one of the vacuum lines.

Here in lies the problem, I have no idea how to do this, it was reccomended to me to leave the engine running and listen for a whistle. I did so, but was unable to hear any whistling. I also tried to squish the lines I could figure, but they all seemed firm and in decent condition still.

Anyone have any suggestions or advice? The car doesnt feel like it is running especially rough, so I am not sure it is even worth investing alot of time.

Thanks for your time!

2 Replies

TIGER-GOAT

MEMBER
2 POSTS

Whoops. That should be 169000 miles, not 16900.

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Thursday, December 2nd, 2010 AT 7:51 PM

KHLOW2008

MECHANIC
41,814 POSTS

Here are the diagnostics for the trouble code.

DTC P0400 (EGR) - EGR FLOW MALFUNCTION

1. Connect SSM. Retrieve DTC(s). Check if DTC P0105, P0106, P0403 or P1102 is present. If DTC(s) is present, diagnose affected DTC(s) first. Manually check EGR valve diaphragm for sticking. After checking, go to CONFIRMATION OF ACTUAL DRIVING PATTERN, clear DTCs and retest. If DTC(s) does not reset, go to next step.

WARNING:
Use extreme caution when checking EGR valve. Valve will be extremely hot and can cause severe burns.

2. Check vacuum hoses for leaks, cracks, clogging or other damage. Check and repair as necessary:

� Pipes and hoses running between throttle body and Backpressure Transducer (BPT)
� Pipe and hose line connecting BPT and EGR solenoid valve
� Hose between EGR solenoid valve and EGR valve
� BPT pressure hose

After checking and repairing, go to CONFIRMATION OF ACTUAL DRIVING
PATTERN. If leakage is not found, go to next step.

3. Turn ignition off. Connect SSM. Set SSM to function mode FD05, to check EGR solenoid operation. EGR solenoid can also be checked by disconnecting EGR solenoid valve harness connector, then connecting an external 12-volt source to EGR solenoid valve.

CAUTION:DO NOT use vehicle battery as 12-volt source. Vehicle electrical system may be damaged.

Start engine. Open throttle valve 5-10 degrees and visually check EGR valve operation. If EGR valve operates, malfunction may be due to freezing or clogging by foreign matter. DO NOT replace EGR valve at this point since it may not be faulty. Go to CONFIRMATION OF ACTUAL DRIVING PATTERN. If malfunction is again detected in CONFIRMATION OF ACTUAL DRIVING PATTERN, check for clogging in gas outlets of intake manifold or cylinder head (check by breathing into outlets). If clogged, repair or replace intake manifold or cylinder head and return to CONFIRMATION OF ACTUAL DRIVING PATTERN. If not clogged, replace EGR valve and go to CONFIRMATION OF ACTUAL DRIVING PATTERN.

Confirmation Of Actual Driving Pattern

� "a" - Conduct CLEAR MEMORY and INSPECTION MODES.
� "b" - Connect SSM to DLC.
� "c" - Start and warm engine until radiator fan completes one cycle (all accessories OFF).
� "d" - Turn SSM on and select function mode FA4.
� "e" - Drive vehicle at 52-58 MPH until LED No. 2 is illuminated.

NOTE:
Keep throttle valve opening steady. Diagnosis will be interrupted if throttle opening varies. Diagnosis starts in 190 seconds after starting engine and requires 4 seconds to run. Transmission should be in Drive range for diagnosis.

� "f" - On SSM, select function mode FB0. Confirm "No Trouble" indication on SSM.