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Tahoe / Yukon Service Manual

DTC P2452 or P2454-P2456

Engine Controls and Fuel - 3.0L LM2 Diesel | Diagnostic Information and Procedures | Document ID: 5508902 Diagnostic Instructions Perform the Diagnostic System Check prior to using this diagnostic procedure: Diagnostic System Check - Vehicle Review the description of Strategy Based Diagnosis: Strategy Based Diagnosis An overview of each diagnostic category can be found here: Diagnostic Procedure Instructions DTC Descriptor DTC P2452 Particulate Filter Pressure Sensor Circuit DTC P2454 Particulate Filter Pressure Sensor Circuit Low DTC P2455 Particulate Filter Pressure Sensor Circuit High DTC P2456 Particulate Filter Pressure Sensor Circuit Intermittent Diagnostic Fault Information

Circuit Short to Ground Open/High Resistance Short to Voltage Signal Performanc
5 V Reference P0641 P2454 P0641* P2452, P2456
Signal P2454 P2455 P2455 P2452, P2456
Low Reference — P2455 — P2452, P2456
* Additional DTCs may set

The diesel exhaust aftertreatment system consists of an under hood catalyst and an underbody catalyst. The underbody catalyst also consists of the main Diesel Oxidation Catalyst and the coated Diesel Particulate Filter (DPF). One of the main purposes of the DPF is to collect particulates from the engine exhaust in order to minimize discharge of soot to the atmosphere. The soot particles accumulate in the channels of the DPF and are burned off at regular intervals through a process called regeneration. This prevents the DPF from clogging. The ECM commands the DPF regeneration after calculating various vehicle conditions such as DPF pressure difference, exhaust gas temperature, engine oil quality, engine speed, etc. Excessive accumulation of the soot in the DPF can cause a drop in the engine performance. During regeneration, additional fuel is injected via multiple post injections in order to increase the exhaust gas temperature. During this period, the DPF temperature is raised to approximately 600°C (1,112°F) and the accumulated soot is oxidized or burned off into carbon dioxide (CO2). Circuit/System Description For an overview of the component/system, refer to: Exhaust Aftertreatment System Description

Circuit Description
5 V Reference Regulated voltage supplied by the control module.
Signal The control module input circuit has an internal resistance connected to ground.
Low Reference Grounded through the control module.
Component Description
B345P Exhaust Pressure Differential Sensor - Particulate Filter The sensor is a capacitive pressure transducer. Electronics in the sensor convert pressure into a digital voltage signal.
K20 Engine Control Module The control module contains a microprocessor used to process input data to control outputs. The control module controls a series of actuators to ensure optimal engine performance. The control module does this by reading values from a variety of sensors, interprets the data and adjusts the engine actuators accordingly.

Conditions for Running the DTC P2452 DTC P2453, P2454, P2455, P2456, or P262B = Not set Engine = Off — For greater than 15 min Ignition and Start Switch Signal = On & Engine = Not Running Frequency the DTC runs = During engine startup & After ignition Off — After the running conditions are met P2454, P2455 Engine = Running Frequency the DTC runs = Continuously — After the running conditions are met — For greater than 3 s P2456 DTC P2454, P2455 = Not set Engine = Running Ignition and Start Signal = Greater than 11 V Frequency the DTC runs = Continuously — After the running conditions are met — For greater than 3 s Conditions for Setting the DTC P2452 Particulate Filter Pressure (Corrected) = Signal not Plausible P2454 Particulate Filter Pressure (Corrected) = Less than −20 kPa (−2.9 PSI) — For greater than 3 s P2455 Particulate Filter Pressure (Corrected) = Greater than 80 kPa (11.6 PSI) — For greater than 3 s P2456 Particulate Filter Pressure (Corrected) = Erratic Actions Taken When the DTC Sets DTCs listed in the DTC Descriptor category = Type B DTC Conditions for Clearing the DTC DTCs listed in the DTC Descriptor category = Type B DTC Diagnostic Aids Certain weather conditions during prolonged drive trips may cause ice to form in the area of the component: B345P Exhaust Pressure Differential Sensor - Particulate Filter If ice is found in the area of the component B345P, clean and dry the component and retest to verify the issue has been corrected. Reference Information Schematic Reference Engine Controls Schematics Connector End View Reference Master Electrical Component List Electrical Information Reference Circuit Testing Connector Repairs Testing for Intermittent Conditions and Poor Connections Wiring Repairs DTC Type Reference Powertrain Diagnostic Trouble Code (DTC) Type Definitions Scan Tool Reference Control Module References Circuit/System Verification

  1. Ignition » On / Vehicle » In Service Mode
  2. Verify DTC P0651 is not set. ⇒ If the DTC is set Refer to: DTC P0641, P0651, P0697, or P06A3 ⇓ If the DTC is not set
  3. Verify DTC P2454, P2455 is not set. ⇒ If any of the DTCs are set Replace the component: B345P Exhaust Pressure Differential Sensor - Particulate Filter ⇓ If none of the DTCs are set
  4. Verify DTC P2456, U0601 is not set. ⇒ If any of the DTCs are set Refer to: Circuit/System Testing ⇓ If none of the DTCs are set
  5. Engine » Idling
  6. Increase the engine speed slowly to 2,000 RPM and then back to idle. Repeat several times Verify the scan tool parameter: Particulate Filter Pressure Sensor = 0 to 10 kPa (0 to 1.5 PSI) ⇒ If not between 0 and 10 kPa (0 and 1.5 PSI) Refer to: Circuit/System Testing ⇓ If between 0 and 10 kPa (0 and 1.5 PSI)
  7. Verify the scan tool parameter: Particulate Filter Pressure Sensor = The value should not spike or drop out. Perform the action while monitoring the parameter: Wiggle the harness and connector: B345P Exhaust Pressure Differential Sensor - Particulate Filter Wiggle the harness and connector: K20 Engine Control Module ⇒ If the value spikes or drops out Repair as necessary » Wiring / Terminal(s) / Electrical Connector(s) ⇓ If the value does not spike or drop out
  8. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data. Verify the DTC does not set. ⇒ If the DTC sets Refer to: Circuit/System Testing ⇓ If the DTC is not set
  9. All OK. Circuit/System Testing
  1. Ignition/Vehicle & All vehicle systems » Off
  2. Disconnect the electrical connector: B345P Exhaust Pressure Differential Sensor - Particulate Filter
  3. Test for less than 10 Ω between the test points: Low Reference circuit terminal 3 & Ground ⇒ If 10 Ω or greater 3.1. Disconnect the electrical connector: X1 @ K20 Engine Control Module 3.2. Test for less than 2 Ω between the test points: Low Reference circuit terminal 3 @ Component harness & The other end of the circuit @ Control module harness ⇒ If 2 Ω or greater » Repair the open/high resistance in the circuit. ⇒ If less than 2 Ω » Replace the component: K20 Engine Control Module ⇓ If less than 10 Ω
  4. Ignition » On / Vehicle » In Service Mode
  5. Test for 4.8 to 5.2 V between the test points: 5 V Reference circuit terminal 1 & Low Reference circuit terminal 3 ⇒ If less than 4.8 V 5.1. Ignition/Vehicle » Off 5.2. Disconnect the electrical connector: X1 @ K20 Engine Control Module 5.3. Test for infinite resistance between the test points: 5 V Reference circuit terminal 1 @ Component harness & Ground ⇒ If less than infinite resistance » Repair the short to ground on the circuit. ⇓ If infinite resistance 5.4. Test for less than 2 Ω between the test points: 5 V Reference circuit terminal 1 @ Component harness & The other end of the circuit @ Control module harness ⇒ If 2 Ω or greater » Repair the open/high resistance in the circuit. ⇒ If less than 2 Ω » Replace the component: K20 Engine Control Module ⇒ If greater than 5.2 V 5.1. Ignition/Vehicle » Off 5.2. Disconnect the electrical connector: X1 @ K20 Engine Control Module 5.3. Ignition » On / Vehicle » In Service Mode 5.4. Test for less than 1 V between the test points: 5 V Reference circuit terminal 1 @ Component harness & Ground ⇒ If 1 V or greater » Repair the short to voltage on the circuit. ⇒ If less than 1 V » Replace the component: K20 Engine Control Module ⇓ If between 4.8 and 5.2 V
  6. Verify the scan tool parameter: Particulate Filter Pressure Sensor = Greater than 4.8 V ⇒ If less than 4.8 V 6.1. Ignition/Vehicle » Off 6.2. Disconnect the electrical connector: X2 @ K20 Engine Control Module 6.3. Test for infinite resistance between the test points: Signal circuit terminal 2 @ Component harness & Ground ⇒ If less than infinite resistance » Repair the short to ground on the circuit. ⇒ If infinite resistance » Replace the component: K20 Engine Control Module ⇓ If greater than 4.8 V
  7. Connect a 3 A fused jumper wire between the test points: Signal circuit terminal 2 & Low Reference circuit terminal 3
  8. Verify the scan tool parameter: Particulate Filter Pressure Sensor = Less than 0.5 V ⇒ If greater than 0.5 V 8.1. Ignition/Vehicle » Off & Remove » Jumper wire(s) 8.2. Disconnect the electrical connector: X2 @ K20 Engine Control Module 8.3. Ignition » On / Vehicle » In Service Mode 8.4. Test for less than 1 V between the test points: Signal circuit terminal 2 @ Component harness & Ground ⇒ If 1 V or greater » Repair the short to voltage on the circuit. ⇓ If less than 1 V 8.5. Ignition/Vehicle » Off 8.6. Test for less than 2 Ω between the test points: Signal circuit terminal 2 @ Component harness & The other end of the circuit @ Control module harness ⇒ If 2 Ω or greater » Repair the open/high resistance in the circuit. ⇒ If less than 2 Ω » Replace the component: K20 Engine Control Module ⇓ If less than 0.5 V
  9. Test or replace the component: B345P Exhaust Pressure Differential Sensor - Particulate Filter Repair Instructions Perform the Diagnostic Repair Verification after completing the repair: Diagnostic Repair Verification Exhaust Pressure Sensor Pipe Replacement - Nitrogen Oxides Catalytic Converter — B345P  Exhaust Pressure Differential Sensor - Particulate Filter For control module replacement, programming, and setup refer to: Control Module References Additional Procedures Particulate Filter Pressure Sensor Reset — Perform only when the following component/system is replaced or serviced: B345P Exhaust Pressure Differential Sensor - Particulate Filter — Replaced