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P220A




DTC P220A or P220B

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.

* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors

DTC P220A
- NOx Sensor 1 Supply Voltage Circuit

DTC P220B
- NOx Sensor 2 Supply Voltage Circuit

Diagnostic Fault Information






Circuit/System Description

The reductant system uses two nitrogen oxide (NOx) sensors to monitor the amount of NOx in the engine's exhaust gas. The first sensor is located at the outlet of the turbocharger and monitors the engine out NOx level. The second NOx sensor is located between the selective catalytic reduction (SCR) and the diesel particulate filter (DPF) and monitors NOx levels downstream of the SCR. The second NOx sensor also provides the engine control module (ECM) with information on the exhaust oxygen level during DPF regeneration.

Each NOx sensor contains a sensing cell, a pumping cell, and a heater. A sample of exhaust gas passes through a diffusion gap between the sensing cell and the pumping cell. The NOx sensor maintains a constant reference voltage across the sensing cell. An electronic circuit within sensor controls the pump current through the pumping cell in order to maintain a constant voltage in the sensing cell. The amount of current required to maintain the reference voltage in the sensing cell is proportional to the concentration of NOx in the exhaust.

The ECM varies the amount of diesel exhaust fluid (DEF) or reductant added by varying the reductant injector duty cycle in response to changes in engine exhaust out NOx levels.

The smart NOx sensors consist of two components, the NOx module and the NOx sensor element that are serviced as a unit. A circuit or performance condition with a NOx sensor is detected by the NOx sensor module. The smart NOx sensor module communicates the condition to the ECM over the serial data line. The ECM sets a DTC when a serial data message is received from the NOx sensor module.

Conditions for Running the DTCs

* The ignition is ON.

* The battery voltage is greater than 11 V.

* The DTCs run continuously once the above conditions are met.

Conditions for Setting the DTC

The ECM receives a serial data message from the GPCM indicating an internal controller circuit fault for greater than 5 s.

Action Taken When the DTC Sets

DTCs P220A and P220B are Type B DTCs.

Conditions for Clearing the DTC

DTCs P220A and P220B are Type B DTCs.

Reference Information

Schematic Reference

Engine Controls Schematics [1][2]Electrical Diagrams

Connector End View Reference

Component Connector End Views 1-2 Shift Solenoid (SS) Valve (M30)

Description and Operation

Diesel Exhaust Fluid (DEF) Warning Strategy (DEF Quality) Diesel Exhaust Fluid (DEF) Warning Strategy (DEF Quality)Diesel Exhaust Fluid (DEF) Warning Strategy (DEF Level) Diesel Exhaust Fluid (DEF) Warning Strategy (DEF Level)Diesel Exhaust Fluid (DEF) Warning Strategy (Emission Control) Diesel Exhaust Fluid (DEF) Warning Strategy (Emission Control)Diesel Exhaust Fluid (DEF) Warning Strategy (Anti-Tampering) Diesel Exhaust Fluid (DEF) Warning Strategy (Anti-Tampering)

Exhaust Aftertreatment System Description Exhaust Aftertreatment System Description

Electrical Information Reference

* Circuit Testing Circuit Testing

* Connector Repairs Connector Repairs

* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections

* Wiring Repairs Wiring Repairs

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References Control Module References for scan tool information

Circuit/System Verification

1. Ignition ON.

2. Verify that DTC P220A or P220B is not set.

• If any of the DTCs are set
Refer to Circuit/System Testing

• If none of the DTCs are set

3. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed in the Freeze Frame/Failure Records data.

4. Verify a DTC does not set.

• If any DTC sets
Refer to Diagnostic Trouble Code (DTC) List - Vehicle Diagnostic Trouble Code (DTC) List - Vehicle for further diagnosis.

• If no DTCs set

5. All OK

Circuit/System Testing

Note: When testing the low reference circuits, verify all vehicle systems are completely OFF for at least 2 minutes. This includes retained accessory power (RAP) and the scan tool.

Refer to Testing Ground and Low Reference Circuits Testing Ground and Low Reference Circuits for further information on testing the low reference circuits.

1. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the appropriate B195 NOx Sensor. It may take up to 2 minutes for all vehicle systems to power down.

2. Test for less than 5 ohms between the low reference circuit terminal 4 and ground.

• If 5 ohms or greater

1. Ignition OFF, disconnect the X2 harness connector at the K34 glow plug control module.

2. Test for less than 2 ohms in the low reference circuit end to end.

• If 2 ohms or greater, repair the open/high resistance in the circuit.

• If less than 2 ohms, replace the K34 glow plug control module.

• If less than 5 ohms

3. Verify that a test lamp does not illuminate between the ignition voltage circuit terminal 1 and ground.

• If the test lamp illuminates

1. Ignition OFF, disconnect the X2 harness connector at the K34 glow plug control module.

2. Test for less than 1 V between the ignition voltage circuit and ground.

• If 1 V or greater, repair the short to voltage on the circuit.

• If the test lamp does not illuminate

4. Ignition ON for greater than 10 s, verify the test lamp illuminates.

• If the test lamp does not illuminate.

1. Ignition OFF, disconnect the X2 harness connector at the K34 glow plug control module.

2. Test for infinite resistance between the ignition circuit and ground.

• If less than infinite resistance, repair the short to ground on the circuit.

• If infinite resistance

3. Test for less than 2 ohms in the ignition circuit end to end.

• If 2 ohms or greater, repair the open/high resistance in the circuit.

• If less than 2 ohms, replace the, K34 glow plug control module.

• The test lamp illuminates

5. Test or replace the appropriate B195 NOx sensor.

Repair Instructions

* Nitrogen Oxide Sensor Replacement - Position 1 Nitrogen Oxide Sensor Replacement - Position 1

* Nitrogen Oxide Sensor Replacement - Position 2 Nitrogen Oxide Sensor Replacement - Position 2

* Perform the scan tool NOx Sensor 1 or 2 Reset procedure after replacing the NOx sensor 1 or 2.

* Perform the Diesel Particulate Filter (DPF) Regeneration Enable Diesel Particulate Filter (DPF) Regeneration Enable

* Control Module References Control Module References for glow plug control module (GPCM) replacement, programming, and setup

Repair Verification

1. Install any components or connectors that have been removed or replaced during diagnosis.

2. Perform any adjustment, programming, or setup procedures that are required when a component or module is removed or replaced.

3. Clear the DTCs.

4. Duplicate the Conditions for Running the DTC and use the Freeze Frame/Failure Records, if applicable, in order to verify the DTC does not reset. If the DTC resets or another DTC is present, refer to Diagnostic Trouble Code (DTC) List - Vehicle Diagnostic Trouble Code (DTC) List - Vehicle and perform the appropriate diagnostic procedure.

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