296 7 ELECTRONIC CONTROL SYSTEMS DIAGNOSTICS
DTC 343 – Excessive EBP (gauge)
DTC 3 43 is set by the ECM when the exhaust back pressure is grea te r than 260 kPa (37.7 ps i) for more
than 2.5 seconds.
Possible Causes Comment
EBP sensor bias high
Check sensor signal voltage. See “EBP Sensor”(page 359) .
EBP signal ground open
Check sensor signal voltage. See “EBP Sensor” (page 359).
Exhaust restriction (muffler or catalytic
converter)
Inspect exhaust. Do “Performance Diagnostics” (page 205).
VGT actuator or vanes stuck closed Do “Performance D iagnostics” (page 205).
VGT control circuit short to B+ Do VGT Pin-Point Diagnostics. See “VGT Actuator” (page 524).
DTC 344 – EBP above spec when engine off
DTC 344 is set by the ECM when the EBP is greater than
300 kPa (43.5 psi) when engine is off or being
cranked for more than 2.5 seconds.
Possible Cause Comment
EBP sensor bias high
Check sensor signal voltage. See “EBP Sensor” (page 359).
EBP sensor or tube line plugged
Clean and retest. Rep la ce if re quired.
DTC 345 – Faults detected during VGT portion of the A MS test
DTC 345 is set by the ECM during the AMS test when the ECM measures the EBP and does not see the
expected response in pressures.
Possible Cause Comment
High intake restriction
Do “Performance Diagnostics” (page 205).
Intake / CAC s ystem leak (pipes, loose
clamps, hoses)
Do “Performance Diagnostics” (page 205).
Exhaust system leak
Do “Performance Diagnostics”
(page 205).
MAP sensor bias
Check sensor signa l voltag e. See “M AP Se ns or” (pag e 50 0 ).
EBP sensor bias
Check sensor signal voltage. See “EBP Sensor” (page 359).
EGR valve stuck open Do “Performance Diagnostic
s” (page 205).
VGT actuator or vanes sticking Do “Performance D iagnostics” (page 205).
EBP sensor or tube plugged
Clean and retest (replace if needed)
Power cylinder integrity
Do “Performance Diagnos
tics” (page 205)
VGT control circuit open or short to
ground
Do VGT Pin-Point Diagnostics. See “VGT Actuator” (page 524).
VGT power and ground circuits Do VGT Pin-Point Diagnostics. See “VGT Actuator” (page 524).
EGES-270-1
Read all safety instructions in the "Safety Information" section of this manual before doing any procedures.
Follow all warnings, cautions, and notes.
© August 2008 Navistar, Inc.
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