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Electronic Control System Gas Plus Engines – FAULT CODE 155

Intake Manifold Temperature Sensor Circuit – Critical Temperature Reached

Overview

Intake Manifold Temperature Sensor Circuit – Critical Temperature Reached

CODE REASON EFFECT
Fault Code: 155
PID: P105
SPN: 105
FMI: 0
LAMP: Red
SRT: 

Intake manifold air temperature high – critical. Intake manifold air temperature signal indicates intake manifold temperature above engine protection critical limit.

Progressive power derate increasing in severity from time of alert. If engine protection shutdown feature is enabled, engine will shutdown 30 seconds after the red stop lamp starts flashing.

Intake Manifold Temperature Sensor Circuit
SMALL | MEDIUM | LARGE

Circuit Description

The electronic control module (ECM) uses the Intake Manifold Pressure/Temperature Sensor input to determine the temperature of the fuel mixture.

Component Location

The intake manifold pressure/temperature sensor is located in the intake manifold housing (combination sensor with absolute pressure).

Shop Talk

All temperature sensors:

  • The resistance of the sensor varies with temperature. The reading you observe should compare to the following table if the sensor is functioning properly.
Temperature (°C) Temperature [°F] Resistance (ohms)
0 32 30k to 36k
25 77 9k to 11k
50 122 3k to 4k
75 167 1350 to 1500
100 212 600 to 675

This sensor can control the engine fan if the OEM utilizes this feature within the ECM. The engine protection shutdown feature is customer-enabled and will require enabling at the customer’s request.

Troubleshooting Steps

STEPS SPECIFICATIONS
STEP 1. Check the fault codes.  
  STEP 1A. Read the fault codes. Fault Code 155 active?
STEP 2. Check the sensor accuracy.  
  STEP 2A. Verify the sensor accuracy with a thermocouple or similar probe. Does the temperature differ more than 3°C or 5°F?
STEP 3. Check the Intake Manifold Pressure/Temperature Sensor.  
  STEP 3A. Inspect the Intake Manifold Pressure/Temperature Sensor and engine harness connector pins. No damaged pins?
  STEP 3B. Read the fault codes. Fault Code 155 active?
STEP 4. Clear the fault codes.  
  STEP 4A. Disable the fault code. Fault Code 155 active?
  STEP 4B. Clear the inactive fault codes. All fault codes cleared?

Guided Step 1 – Check the fault codes.

Guided Step 1A – Read the fault codes.

Conditions

  • Turn keyswitch ON
  • Connect the INSITE™ electronic service tool.

Action

Use INSITE™ electronic service tool to read the fault codes.

Fault Code 155 active?
YES NO
No Repair No Repair

Guided Step 2 – Check the sensor accuracy.

Guided Step 2A – Verify the sensor accuracy with a thermocouple or similar probe.

Conditions

  • Connect the INSITE™ electronic service tool
  • Turn keyswitch ON.

Action

  • Compare the intake manifold temperature reading on INSITE™ electronic service tool to the reading from the probe.

Note: If no temperature measuring device is available, answer “NO” to this step.

Does the temperature differ more than 3°C or 5°F?
YES NO

Replace the Intake Manifold Intake Pressure/Temperature Sensor. Refer to Procedure 019-099.

 No Repair

Guided Step 3 – Check the Intake Manifold Pressure/Temperature Sensor.

Guided Step 3A – Inspect the Intake Manifold Pressure/Temperature Sensor and engine harness connector pins.

Conditions

  • Turn keyswitch OFF.
  • Disconnect the engine harness from the Intake Manifold Pressure/Temperature Sensor.

Action

  • Corroded pins
  • Bent or broken pins
  • Pushed back or expanded pins
  • Moisture in or on the connector
  • Missing or damaged connector seals
  • Dirt or debris in or on the connector pins.

Dirty or damaged pins?
YES NO

Repair or replace the engine harness, or replace the sensor, whichever has the damaged pins.

  • Flush the dirt, debris, or moisture from the connector pins using electronic contact cleaner, Part Number 3824510.
  • Install the appropriate connector seal if it is damaged or missing.
  • Repair the engine harness. Refer to Procedure 019-205.
  • Replace the engine harness. Refer to Procedure 019-043.
  • Replace the sensor. Refer to Procedure 019-099.
 No Repair

Guided Step 3B – Read the fault codes.

Conditions

  • Connect all components
  • Turn keyswitch ON.

Action

  • Start the engine and let it idle for one minute.
  • Use INSITE™ electronic service tool to read the fault codes.

Fault Code 155 active?
YES NO

Refer to the Intake Manifold Air Temperature Above Normal troubleshooting symptom chart in Section TS in the Troubleshooting and Repair Manual C Gas, C Gas Plus, and L Gas Plus Engines, Bulletin 3666206 or the Troubleshooting and Repair Manual B5.9G, B5.9LPG, B Gas Plus, and B LPG Plus Engines, Bulletin 3666164.

 No Repair

Guided Step 4 – Clear the fault codes.

Guided Step 4A – Disable the fault code.

Conditions

  • Connect all components
  • Turn keyswitch ON.

Action

  • Start the engine and let it idle for one minute.
  • Verify that Fault Code 155 is inactive.

Fault Code 155 active?
YES NO

Troubleshooting procedures need to be repeated from the beginning.

 No Repair

Guided Step 4B – Clear the inactive fault codes.

Conditions

  • Connect all components
  • Turn keyswitch ON.

Action

  • Use INSITE™ electronic service tool to erase the inactive fault codes .

All fault codes cleared?
YES NO
No Repair

Troubleshoot any remaining active fault codes.
Repair complete
Appropriate troubleshooting charts
Last Modified:  03-Aug-2004
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