Go look it up in your factory model/year-specific PCED, not AutoZone's lame-a$$ generic data.
Steve
Actually, my "lame-a$$" (sic) Actron generic scan disk shows that code for 1998 and 1996 too. I'm pretty sure if the "lame-a$$" (sic) code list in the "Old" Main Site FAQ were not down, it would show the P0400 code as a EGR malfunction code too.
Edit. From my "lame-a$$" (sic) PCED for 1996 Ford Contour
HE130 DTC P0400: ACCESS DPFEGR PID WITH SCAN TOOL
Diagnostic Trouble Code (DTC) P0400 indicates that Self-Test has detected an EGR system malfunction.
Possible causes:
-- Any EGR system failure.
l Key on, engine off.
l Access DPFEGR PID (formerly DPFE) with a Scan Tool.
NOTE:
Differential pressure feedback EGR (D.P.F. EGR) sensor input with no EGR flow is 0.45 volts ± 0.25 volts.
l Is DPFEGR PID voltage less than 0.2 volts?
Yes
The D.P.F. EGR sensor voltage is less than the acceptable minimum. GO to «HE134».
No
GO to «HE131».
HE134 INDUCE OPPOSITE D.P.F. EGR SENSOR SIGNAL
l Key off.
l Disconnect D.P.F. EGR sensor vehicle harness connector.
l Connect a jumper wire between the sensor VREF circuit and DPFE SIG circuit at the D.P.F. EGR sensor vehicle harness connector.
l Key on, engine off.
NOTE:
If a Scan Tool communication problem exists, remove jumper immediately and go directly to «HE135».
l Access DPFEGR PID with a Scan Tool.
l Is DPFEGR PID value between 4.0 and 6.0 volts?
Yes
REPLACE damaged D.P.F. EGR sensor. RECONNECT all components. COMPLETE PCM Reset to clear DTCs (REFER to Section 2A, «Powertrain Control Module (PCM) Reset»). RERUN «Quick Test».
No
REMOVE jumper. GO to «HE135».
HE135 MEASURE VREF VOLTAGE AT D.P.F. EGR SENSOR VEHICLE HARNESS CONNECTOR
l D.P.F. EGR sensor disconnected.
l Key on, engine off.
l Measure voltage between the sensor VREF circuit and SIG RTN circuit at the D.P.F. EGR sensor vehicle harness connector.
l Is VREF voltage between 4.0 and 6.0 volts?
Yes
GO to «HE136».
No
VREF voltage is out of range. GO to Pinpoint Test Step «C1».
HE136 CHECK DPFE SIG CIRCUIT FOR SHORTS TO GROUND AND SIG RTN
l Key off.
l D.P.F. EGR sensor disconnected.
l Disconnect PCM. Inspect for damaged or pushed out pins, corrosion, loose wires, etc. Service as necessary.
l Install breakout box, leave PCM disconnected.
l Measure resistance between Test Pin 65 (DPFE SIG) and Test Pin 91 (SIG RTN) and Test Pins 51 and 103 (PWR GND) at the breakout box.
l Is each resistance greater than 10,000 ohms?
Yes
REPLACE damaged PCM. REMOVE breakout box. RECONNECT all components. RERUN «Quick Test».
No
SERVICE short circuit between DPFE SIG and GROUND or SIG RTN. REMOVE breakout box. RECONNECT all components. RERUN «Quick Test».
HE131 CHECK FOR HIGH D.P.F. EGR SENSOR VOLTAGE
l Key on, engine off.
l Is DPFEGR PID voltage greater than 4.0 volts?
Yes
The D.P.F. EGR sensor voltage is greater than the acceptable maximum. GO to «HE137».
No
GO to «HE132».
HE137 CHECK DPFE SIG CIRCUIT FOR SHORT TO PWR
l Key off.
l Disconnect D.P.F. EGR sensor vehicle harness connector.
l Key on, engine off.
l Measure voltage between DPFE SIG circuit at the D.P.F. EGR sensor vehicle harness connector and battery ground.
l Is voltage greater than 10.5 volts?
Yes
The D.P.F. EGR sensor voltage is indicating a short to PWR. GO to «HE138».
No
GO to «HE139».
HE138 CHECK DPFE SIG CIRCUIT FOR SHORT TO PWR IN HARNESS
l Key off.
l D.P.F. EGR sensor disconnected.
l Disconnect PCM. Inspect for damaged or pushed out pins, corrosion, loose wires, etc. Service as necessary.
l Install breakout box, leave PCM disconnected.
l Key on, engine off.
l Measure voltage between Test Pin 65 (DPFE SIG) and Test Pins 51 and 103 (PWR GND) at the breakout box.
l Is voltage greater than 10.5 volts?
Yes
SERVICE short between DPFE SIG and PWR circuit. REMOVE breakout box. RECONNECT all components. RERUN «Quick Test».
No
REPLACE damaged PCM. REMOVE breakout box. RECONNECT all components. RERUN «Quick Test».
HE139 INDUCE OPPOSITE D.P.F. EGR SENSOR SIGNAL
l Key off.
l Disconnect D.P.F. EGR sensor vehicle harness connector.
l Connect a jumper wire between the sensor DPFE SIG circuit and SIG RTN circuit at the D.P.F. EGR sensor vehicle harness connector.
l Key on, engine off.
NOTE:
If a Scan Tool communication problem exists, remove jumper immediately and go directly to «HE144».
l Access DPFEGR PID with a Scan Tool.
l Is DPFEGR PID voltage less than 0.05 volts?
Yes
REMOVE jumper. GO to «HE140».
No
Unable to induce opposite signal. GO to «HE142».
