I was driving around today and "got on it" and my check engine light came on. I hooked up my code reader and got these three codes:P1443= I cant find this code in the book. P0401=EGR Flow Insufficient and P0171= system too lean. Does anyone know what the first code is and possibly what the faulty part is. I'm thinking bad EGR valve or sensor.

 

DTC P1443: MONITOR IDLE AIR CONTROL DUTY CYCLE (IAC AT IDLE)

Continuous Memory Diagnostic Trouble Code (DTC) P1443 can be initiated by an IAC valve speed error sometime during vehicle operation. If a Continuous Memory DTC P1507 is received with the DTC P1443 in Self-Test, GO directly to Pinpoint Test Step «KE30».

NOTE:
The following overspeed check is to be performed on flexible fuel vehicles.

l Key on, engine off.

l Connect scan tool.

l Access IAC, TP, and RPM PIDs.

l With engine at normal operating temperature, accessories off and at idle, the IAC duty cycle should be between 20% to 45%.

l Observe the IAC and RPM PIDs for an indication of a fault while performing the following:

-- While at idle, wiggle the IAC valve connector and vehicle harness between the IAC valve and PCM. A fault is indicated by a sudden increase in rpm and decrease in duty cycle.

-- Rapidly (or quickly) press and release the throttle several times while looking for slow return to idle (observing the TP PID). This may indicate a sticking IAC valve.

l Is a fault indicated?

Yes
ISOLATE fault and REPAIR as necessary. RESTORE vehicle. COMPLETE PCM Reset to clear DTCs. RERUN «Quick Test». VERIFY a symptom no longer exists.

No
GO to «HW8».

 

HE70 DTC P0401: RUN KOER SELF-TEST

Diagnostic Trouble Code (DTC) P0401 indicates that Continuous Memory Self-Test has detected insufficient EGR flow.

Possible causes:

-- EGR valve stuck closed or iced.

-- EGR valve diaphragm leaks.

-- EGR valve or flow path restricted.

-- EGR vacuum hose off, plugged or leaks.

-- VPWR circuit open to EGR Vacuum Regulator (EGR V.R.) solenoid.

-- EVR circuit to PCM open.

-- EVR circuit to PCM shorted to PWR.

-- Differential Pressure Feedback EGR (D.P.F. EGR) sensor pressure hoses both off.

-- D.P.F. EGR sensor pressure hoses reversed.

-- D.P.F. EGR sensor VREF circuit open.

-- Downstream pressure hose off.

-- Downstream pressure hose plugged.

-- Damaged orifice tube assembly.

-- Damaged EGR V.R. solenoid.

-- Damaged D.P.F. EGR sensor.

-- Damaged PCM.

l Run KOER Self-Test.

l Is KOER DTC P1408 output?

Yes
The KOER Self-Test has detected an EGR fault that is currently present. GO to «HE71».

No
REMOVE and INSPECT the EGR Valve and intake manifold EGR port for restriction. If OK, the fault that produced DTC P0401 is intermittent. GO to «HE90».

 

H41 DTCs P0172, P0174, P0171 AND P0175: FUEL SYSTEM AT THE CORRECTED ADAPTIVE LIMITS

Diagnostic Trouble Codes (DTCs) P0171 bank (1) (cylinder #1) and DTC P0174 bank (2) indicate the fuel/air ratio is too lean. The fuel adaptive system is at the rich correction limit.

DTC P0172 bank (1) and DTC P0175 bank (2) indicate the fuel/air ratio is too rich. The fuel adaptive system is at the lean correction limit.

DTCs HO2S Reference list:

-- HO2S-11 = DTCs P0171 and P0172

-- HO2S-21 = DTCs P0174 and P0175

Possible causes:

Fuel system

-- Excessive fuel pressure.

-- Leaking fuel injector(s).

-- Leaking fuel pressure regulator.

-- Low fuel pressure.

-- Contaminated injector(s)

Induction system

-- Air leaks after the MAF.

-- Vacuum leaks.

-- Restricted air inlet.

-- PCV system.

-- Fuel purge system.

-- Improperly seated dip stick.

EGR

-- Leaking gasket.

-- Stuck open EGR valve.

-- Leaking diaphragm.

Base engine

-- Oil overfill.

-- Cam timing.

-- Cylinder compression.

-- Exhaust leaks before or near the HO2S's.

l Check air intake for leaks, obstructions and damage.

l Check air filter, air filter housing for blockage.

l Verify integrity of the PCV system.

l Check for vacuum leaks.

l Are there any of the above concerns?

Yes
SERVICE as necessary. RERUN «Quick Test».

No
GO to Pinpoint Test Step «DC25». If MAF reading is within specification, return to Pinpoint Test Step «H42».

 

Sorry for loading you up with all that info. I just copied and pasted each DTC from my service manual CD. If you'd like to see any of the called for pinpoint tests just let me know and i'll post em up.

 

actually, it was a simple fix. The vacuum lines that plug into the vacuum canister by the alternator came unplugged. I hooked it back up and cleared the codes and no ploblems since.

 

Hehehehehe, gotta love it. OBD-II-equipped truck, computer that monitors the engine/tranny to within an in of their lives and the problem is one of the oldest and most common points of failure in ANY vehicle since about 1908.... vacuum leak! I find that extremely funny/ironic.