GEAR (32 teeth) 7P9576 - Caterpillar

Table 1
Diagnostic Trouble Codes for Low Intake Manifold Air Pressure
J1939 Code Description Notes
1127-18 Engine Turbocharger 1 Boost Pressure : Low - moderate severity (2) The Electronic Control Module (ECM) detects the following conditions:
The actual intake manifold air pressure is less than the desired intake manifold air pressure for at least 10 seconds. The difference between the two values depends on engine operating conditions.
The engine speed is between 1000 rpm and 2300 rpm.
The engine coolant temperature is greater than 45° C (113° F).
There are no active 102 diagnostic codes for the intake manifold air pressure sensor.
There is no other active engine derates.
If equipped, the warning lamp will flash. The engine will be derated.
The fault will be cleared when the intake manifold air pressure is within the acceptable range for at least 11 minutes. Probable Causes
Intake air filter
Air intake system
Wastegate regulator
TurbochargerRecommended Actions
Note: The procedures have been listed in order of probability. Complete the procedures in order.
Table 2
Troubleshooting Test Steps Values Results
1. Intake Air Filter
A. Check the air filter restriction indicator, if equipped.
B. Ensure that the air filter is clean and serviceable.
Air filter
Result: The air filter is blocked.
Repair: Replace the air filter element. Refer to the Operation and Maintenance Manual, "Engine Air Cleaner Element - Replace".
Result: The air filter is OK.
Proceed to Test Step 2.
2. Air Intake System
A. Check the air intake system for the following defects:
Blockages
Restrictions
Damage to the air intake ducts and hoses
Loose connections and air leaks
Air intake
Result: The air intake system is blocked, restricted, damaged, or loose.
Repair: Make all necessary repairs to the air intake system.
Result: The air intake system is OK.
Proceed to Test Step 3.
3. Wastegate Regulator
A. Use the electronic service tool to check for diagnostic trouble codes that relate to the wastegate regulator.
Wastegate regulator
Result: Diagnostic codes are present that relate to the wastegate regulator.
Repair: Rectify the cause of any related codes. Refer to Troubleshooting, "Diagnostic Trouble Codes".
Result: There are no diagnostic codes that relate to the wastegate regulator.
Proceed to Test Step 4.
4. Turbocharger
Note: The turbocharger that is installed on the engine is a nonserviceable item. If any mechanical fault exists, then the turbocharger must be replaced.
A. Check that the compressor housings for the turbochargers are free of dirt and debris.
B. Check that the turbine housings for the turbochargers are free of dirt and debris.
C. Check that the turbine blades rotate freely in the turbochargers.
Turbocharger
Result: There is a fault with the turbocharger.
Repair: Replace the turbocharger. Refer to Disassembly and Assembly, "Turbocharger - Remove" and Disassembly and Assembly, "Turbocharger - Install".
Result: The turbocharger is OK.
Contact the Dealer Solution Network (DSN).