P20B1 Possible Causes

• Faulty reductant heater coolant control valve
• Reductant heater coolant control valve circuit open or shorted
• Poor electrical connection in reductant heater coolant control valve circuit

What Does It Mean?

How to Fix Code P20B1

Check the “possible causes” listed above. Visually inspect related wiring harnesses and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector pins.

P20B1 Possible Symptoms

Illuminated engine light (or service engine soon warning light)

P20B1 Meaning

Reductant heater coolant control valve circuit/open is the generic description for code P20B1, but the manufacturer may have a different description

P20B2 Possible Causes

• Faulty reductant heater coolant control valve
• Reductant heater coolant control valve harness is open or shorted
• Poor electrical connection in reductant heater coolant control valve circuit

What Does It Mean?

How to Fix Code P20B2

Check the “possible causes” listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector pins.

P20B2 Possible Symptoms

Check engine light on (or service engine soon warning light)

P20B2 Meaning

Reductant heater coolant control valve performance is the generic description for code P20B2, but the manufacturer may have a different description.

P20B3 Possible Causes

• Faulty reductant heater coolant control valve
• Reductant heater coolant control valve harness is open or shorted
• Poor electrical connection in reductant heater coolant control valve circuit

What Does It Mean?

How to Fix Code P20B3

Check the “possible causes” listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector pins.

P20B3 Possible Symptoms

Check engine light on (or service engine soon warning light)

P20B3 Meaning

Reductant heater coolant control valve circuit is the generic description for code P20B3, but the manufacturer may have a different description.

P20B4 Possible Causes

• Faulty reductant heater coolant control valve
• Reductant heater coolant control valve harness is open or shorted
• Poor electrical connection in the reductant heater coolant control valve circuit

What Does It Mean?

How to Fix Code P20B4

Check the “possible causes” listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector pins.

Possible Symptoms

Check engine light on (or service engine soon warning light)

P20B4 Meaning

Reductant heater coolant control valve circuit high is the generic description for code P20B4, but the manufacturer may have a different description.

P20B5 Possible Causes

• Faulty reductant measurement unit heater control
• Reductant measurement unit heater control harness is open or shorted
• Electrical connection of reductant measurement unit heater control circuit

What Does It Mean?

How to Fix Code P20B5

Check the “possible causes” listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector pins.

P20B5 Possible Symptoms

Engine light on (or service engine soon warning light)

P20B5 Meaning

Reductant measurement unit heater control circuit/open is the generic description for code P20B5, but the manufacturer may have a different description.

P20B6 Possible Causes

• Faulty reductant metering unit heater control
• Reductant metering unit heater control harness is open or shorted
• Reductant metering unit heater control circuit electrical connection

What Does It Mean?

How to Fix Code P20B6

Check the “Possible Causes” listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector pins.

P20B6 Possible Symptoms

Engine Light ON (or Service Engine Soon Warning Light)

P20B6 Meaning

Reductant metering unit heater control circuit performance is the generic description for code P20B6, but the manufacturer may have a different description.

P20B7 Possible Causes

• Faulty reductant measurement unit heater control
• Reductant measurement unit heater control harness open or shorted
• Reductant measurement unit heater control circuit electrical connection

What Does It Mean?

How to Fix Code P20B7

Check the “possible causes” listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector pins.

P20B7 Possible Symptoms

Engine light on (or service engine soon warning light)

P20B7 Meaning

Reductant measurement unit heater control circuit low is the generic description for code P20B7, but the manufacturer may have a different description.

P20B8 Possible Causes

• Faulty reductant measurement unit heater control
• Reductant measurement unit heater control circuit open or shorted
• Reductant measurement unit heater control circuit electrical connection

What Does It Mean?

How to Fix Code P20B8

Check the “possible causes” listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector pins.

P20B8 Possible Symptoms

Engine light on (or service engine soon warning light)

P20B8 Meaning

Reductant measurement unit heater control circuit high is the generic description for code P20B8, but the manufacturer may have a different description.

How severe is this DTC?

A stored P20B9 code should be considered serious and addressed as soon as possible. The SCR system may be disabled because of this. Catalyst damage could occur if the conditions that contributed to the code being stored are not corrected in a timely manner.

What are some of the symptoms of the code?

Symptoms of a P20B9 trouble code may include:

• Decreased engine performance
• Excessive black smoke from the vehicle’s exhaust
• Reduced fuel efficiency
• Other SCR-related codes

What are some common causes of the code?

Causes

of this code may include:

• Faulty reductant heater
• Open or shorted circuits in the reductant heater control
• Defective reductant temperature sensor
• Faulty SCR controller/PCM or programming error

What are the troubleshooting steps for P20B9?

You will need access to a diagnostic scanner, a digital volt/ohmmeter (DVOM), and a source of vehicle-specific diagnostic information to diagnose a P20B9 code.

If you can find a technical service bulletin (TSB) that matches the vehicle’s year, make, and model; as well as the engine size, stored code(s), and presented symptoms, it might provide useful diagnostic information.

You’ll want to start your diagnosis with a visual inspection of the reductant heater system’s wiring harnesses and connectors. Burned or damaged wiring and/or connectors should be repaired or replaced before continuing.

Proceed by connecting the scanner to the vehicle’s diagnostic connector and retrieving all stored codes and relevant freeze frame data. Note this information before clearing the codes and test drive the vehicle until the PCM enters readiness mode or the code resets.

The code is intermittent and may be much harder to diagnose (for now), if the PCM enters readiness mode. If this is the case, the conditions that contributed to the code being stored may need to worsen before an accurate diagnosis can be made.

If the code resets, consult your vehicle information source for diagnostic flowcharts, connector pinout diagrams, connector face views, as well as component testing procedures and specifications. This information will be needed to complete the next step of your diagnosis.

Use the DVOM to test the SCR control system’s power supply. Test fuses with the circuit loaded to avoid misdiagnosis. If proper power (battery voltage) and ground circuits are found, use the scanner to activate the reductant heater(s) and test the output control circuit voltage. If voltage is insufficient, suspect a faulty controller or programming error.

If the output voltage circuit is within parameters, use the DVOM to test the reductant heater in question. If the heater does not meet manufacturer specifications, suspect it has failed.

If this code appears in warm weather, suspect a programming error has occurred

How severe is this DTC?

A stored P20BA code should be considered severe and addressed as soon as possible. The SCR system may be disabled because of this. Catalyst damage could occur if the conditions that contributed to the code being stored are not corrected in a timely manner.

What are some of the symptoms of the code?

Symptoms of a P20BA fault code may include:

• Decreased engine performance
• Excessive black smoke from the vehicle’s exhaust
• Reduced fuel efficiency
• Other SCR-related codes

What are some common causes of the code?

Causes

of this code may include:

• Faulty reductant heater
• Open or shorted circuits in the reductant heater control
• Defective reductant temperature sensor
• Faulty SCR controller/PCM or programming error

What are the troubleshooting steps for P20BA?

You will need access to a diagnostic scanner, a digital volt/ohmmeter (DVOM), and a source of vehicle-specific diagnostic information to diagnose a P20BA code.

If you can find a technical service bulletin (TSB) that matches the vehicle’s year, make, and model; as well as the engine size, stored code(s), and presented symptoms, it could provide helpful diagnostic information.

You’ll want to start your diagnosis with a visual inspection of the reductant heater system’s wiring harnesses and connectors. Burned or damaged wiring and/or connectors should be repaired or replaced before continuing.

Proceed by hooking up the scanner to the vehicle’s diagnostic connector and retrieving all stored codes and relevant freeze frame data. Note this information before clearing the codes and test drive the vehicle until the PCM enters readiness mode or the code resets.

The code is intermittent and may be much harder to diagnose (for the time being) if the PCM enters readiness mode. If this is the case, the conditions that contributed to the code being stored may need to worsen before an accurate diagnosis can be made.

If the code resets, consult your vehicle information source for diagnostic flowcharts, connector pinout diagrams, connector face views, as well as component testing procedures and specifications. This information will be needed to complete the next step of your diagnosis.

Use the DVOM to test the SCR/control system’s power supply. Test fuses with the circuit loaded to avoid misdiagnosis. If proper power (battery voltage) and ground circuits are found, use the scanner to activate the reductant heater(s) and test the output control circuit voltage. If voltage is insufficient, suspect the controller is faulty or has encountered a programming error.

If the output voltage circuit is within parameters, use the DVOM to test the reductant heater element in question. If the heater does not meet manufacturer specifications, suspect it has failed.

If this code appears in warm weather, suspect a programming error has occurred…