DTC P04DB, P04E2, P04E3, or P04FB

Engine Controls and Fuel - 3.0L LM2 Diesel | Diagnostic Information and Procedures | Document ID: 5507633 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 Crankcase Ventilation System Disconnected DTC P04DB Crankcase Ventilation Hose Connection Pressure Sensor Circuit Low DTC P04E2 Crankcase Ventilation Hose Connection Pressure Sensor Circuit High DTC P04E3 Crankcase Ventilation Hose Connection Pressure Sensor Performance DTC P04FB Diagnostic Fault Information

Circuit	Short to Ground	Open/Hi Resistan	Short gh to ceVoltage	Signal Performa
5 V Reference	P04E2, P0651, P146D**	P04E2, P146D**	P0651	P04FB
Signal	P04E2	P04E2	P04E3	P04DB, P04FB
Low Reference	—	P04E3, P146D**	—	P04FB
** — Additional DTCs may set

Typical Scan Tool Data Crankcase Ventilation Hose Connection Pressure Sensor

	Circuit	Short to Ground	Open	Short to Voltage
	Operating Conditions: Engine = Idling — At normal operating temperature. Accessories = Off Parameter Normal Range: −1 to 1 kPa (−0.1 to 0.1 PSI)
	5 V Reference	−6 kPa (−0.9 PSI)	0 kPa (0.0 PSI)	0 kPa (0.0 PSI)

Circuit	Short to Ground	Open	Short to Voltage
Signal	−6 kPa (−0.9 PSI)	6 kPa (0.9 PSI)	6 kPa (0.9 PSI)
Low Reference	—	6 kPa (0.9 PSI)	—

Circuit/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 5 V.
Low Reference	Grounded through the control module.

Component	Description
B321 Crankcase Pressure Sensor	The sensor is a capacitive pressure transducer. Electronics in the sensor convert pressure into an analog 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.

This diagnostic monitors the performance of the Positive Crankcase Ventilation (PCV) System. The sensor B321 is mounted between the following components: Engine Crankcase & Induction System The pressure sensor is a pressure transducer which outputs a voltage proportional to the gauge pressure between the crankcase ventilation hose and the atmosphere. The sensor B321 measures the pressure change that varies in conjunction with the engine air flow and pressure pulses as the cylinders go up and down in the crankcase. Conditions for Running the DTC P04DB DTC P0071, P0072, P0073, P0074, P0101, P0102, P0103, P0106, P0107, P0108, P010B, P010C, P010D, P14B6, P2227, P2228, P2229, P2230, U060F, U1346, U2011 = Not set DTC P04E2, P04E3 = Not pending Ambient Air Temperature = Warmer than −19°C (2°F) Barometric Pressure = Greater than 67 kPa (9.7 PSI) Engine Coolant Temperature = Warmer than 70°C (158°F) Engine Speed = 1,000 to 4,500 RPM Mass Airflow Sensor = 120 to 250 g/s & Stable Manifold Absolute Pressure Sensor = −220 to −100 kPa (−31 to −14.5 PSI) Frequency the DTC runs = Continuously — After the running conditions are met — For greater than 1 s P04E2, P04E3 System Voltage = Greater than 11.0 V Frequency the DTC runs = Continuously — After the running conditions are met P04FB Engine Coolant Temperature = Warmer than 70°C (158°F) Time between current ignition cycle and the last time the engine was running = Greater than 9 s Frequency the DTC runs = Continuously — After the running conditions are met Conditions for Setting the DTC P04DB Crankcase Ventilation Hose Connection Pressure Sensor = The actual value is not within a predetermined range of the calculated value P04E2 Crankcase Ventilation Hose Connection Pressure Sensor = Less than 0.22 V — For greater than 3 s P04E3 Crankcase Ventilation Hose Connection Pressure Sensor = Greater than 4.78 V — For greater than 3 s P04FB Crankcase Ventilation Hose Connection Pressure Sensor ≠ −1 to 1 kPa (−0.1 to 0.1 PSI) — For greater than 1 s Actions Taken When the DTC Sets DTCs listed in the DTC Descriptor category = Type B DTC Reduced Engine Power = Active P16 Instrument Cluster = Reduced Engine Power Warning Message = Service Emission System /Service Exhaust Fluid System Conditions for Clearing the DTC DTCs listed in the DTC Descriptor category = Type B DTC Diagnostic Aids Certain engine mechanical conditions may cause excess oil to accumulate in the cam cover area near the sensor. If this condition exists, excess oil may momentarily restrict the passage to the sensor which may cause P04DB to set. Reference Information 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

Ignition » On / Vehicle » In Service Mode
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
Verify the scan tool parameter: Crankcase Ventilation Hose Connection Pressure Sensor = −6.00 to 6.00 kPa (−0.80 to 0.80 PSI) ⇒ If not between −6.00 and 6.00 kPa (−0.80 and 0.80 PSI) Refer to: Circuit/System Testing ⇓ If between −6.00 and 6.00 kPa (−0.80 and 0.80 PSI)
Verify the scan tool parameter: Crankcase Ventilation Hose Connection Pressure Sensor = −0.63 to 0.63 kPa (−0.09 to 0.09 PSI) ⇒ If not between −0.63 and 0.63 kPa (−0.09 and 0.09 PSI) 4.1. Ignition/Vehicle » Off 4.2. Remove the component: B321 Crankcase Pressure Sensor — Leave the electrical connector connected. 4.3. Ignition » On / Vehicle » In Service Mode 4.4. Verify the scan tool parameter: Crankcase Ventilation Hose Connection Pressure Sensor = −0.63 to 0.63 kPa (−0.09 to 0.09 PSI) ⇒ If not between −0.63 and 0.63 kPa (−0.09 and 0.09 PSI) Replace the component: B321 Crankcase Pressure Sensor ⇓ If between −0.63 and 0.63 kPa (−0.09 and 0.09 PSI) 4.5. Refer to step 8 ⇓ If between −0.63 and 0.63 kPa (−0.09 and 0.09 PSI)
Engine » Idling

Verify the scan tool parameter: Crankcase Ventilation Hose Connection Pressure Sensor = The value should change with accelerator pedal input. ⇒ If the parameter value does not change Refer to: Circuit/System Testing ⇓ If the parameter value changes
Verify the scan tool parameter: Crankcase Ventilation Hose Connection Pressure Sensor = The value should not spike or drop out. Perform the action while monitoring the parameter: Wiggle the harness and connector: B321 Crankcase Pressure Sensor 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
Verify the following conditions do not exist: Positive Crankcase Ventilation System — Hoses / Lines – Leaking — Loose Clamps / Visible Damage – Restricted — Collapsed / Kinked B65 Intake Manifold Pressure and Air Temperature Sensor — Leaking @ O-Ring — Missing / Visible Damage B321 Crankcase Pressure Sensor — Leaking @ O-Ring — Missing / Visible Damage Air Cleaner Element — Dirty / Missing / Restricted Intake Air Duct & Intake Manifold — Cracked / Loose Clamps / Restricted / Visible Damage » Refer to: Intake Manifold Replacement — Cleaning and Inspection Procedure - Conditional Oil consumption – Piston Ring — Worn – Valve Guide — Worn – Valve Stem Oil Seal — Leaking Refer to: Oil Consumption Diagnosis ⇒ If a condition exists Repair or replace as necessary ⇓ If no condition exists
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 Repeat the procedure starting at step 3 ⇓ If the DTC is not set
All OK. Circuit/System Testing

Ignition/Vehicle & All vehicle systems » Off
Disconnect the electrical connector: B321 Crankcase Pressure Sensor
Test for less than 5 Ω between the test points: Low Reference circuit terminal 3 & Ground ⇒ If 5 Ω or greater 3.1. Disconnect the appropriate electrical connector: 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 5 Ω
Ignition » On / Vehicle » In Service Mode
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 appropriate electrical connector: 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 appropriate electrical connector: 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
Verify the scan tool parameter: Crankcase Ventilation Hose Connection Pressure Sensor = Less than 0.2 V ⇒ If 0.2 V or greater 6.1. Ignition/Vehicle » Off 6.2. Disconnect the appropriate electrical connector: K20 Engine Control Module 6.3. Ignition » On / Vehicle » In Service Mode 6.4. 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 » Replace the component: K20 Engine Control Module ⇓ If less than 0.2 V
Connect a 3 A fused jumper wire between the test points: Signal circuit terminal 2 & 5 V Reference circuit terminal 1
Verify the scan tool parameter: Crankcase Ventilation Hose Connection Pressure Sensor = Greater than 4.7 V ⇒ If 4.7 V or less 8.1. Ignition/Vehicle » Off & Remove » Jumper wire(s) 8.2. Disconnect the appropriate electrical connector: K20 Engine Control Module 8.3. 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 8.4. 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 greater than 4.7 V
Test or replace the component: B321 Crankcase Pressure Sensor Repair Instructions Perform the Diagnostic Repair Verification after completing the repair: Diagnostic Repair Verification Crankcase Pressure Sensor Replacement For control module replacement, programming, and setup refer to: Control Module References Additional Procedures

Ignition » On / Vehicle » In Service Mode
Verify that all scan tool Event Data parameters under the following data list displays No: Exhaust Gas Recirculation System Malfunction Warning Event Data ⇒ If not the specified state Operate the vehicle within the Conditions for Running the DTC for the DTC identified by the Event Data parameter displaying Yes. ⇓ If the specified state
All OK.