P20FA – Reductant Pump Control Circuit Low

Urgency and Immediate Actions

The P20FA code indicates a critical issue with the reductant pump control circuit in diesel vehicles equipped with Selective Catalytic Reduction (SCR) systems. This problem is considered serious and can lead to damage if not addressed promptly.

Severity: High
Continued Driving: Not recommended
Dealer Attention: Advised as soon as possible

While the vehicle may still be operational, continuing to drive with this code active can potentially damage the SCR system and lead to reduced engine performance or even engine shutdown. It is strongly recommended to have the vehicle inspected by a qualified technician or dealership as soon as possible.

Code Specifics

P20FA is a generic powertrain code related to the vehicle's emissions control system. The code definition is:

• P = Powertrain
• 20 = Fuel and air metering (injector circuit)
• FA = Specific fault index

This code specifically refers to an open circuit in the control system for Reductant Pump 'B'. While it is a generic code, the exact implementation and system design may vary between manufacturers.

Components Involved

The main components involved in this fault code are:

1. Reductant Pump 'B': Responsible for delivering Diesel Exhaust Fluid (DEF) to the SCR system.
2. Control Circuit: The electrical pathway that controls the reductant pump's operation.
3. Powertrain Control Module (PCM): Monitors and controls the reductant system.
4. Wiring Harness: Connects the PCM to the reductant pump.
5. SCR System: Uses DEF to reduce NOx emissions in diesel exhaust.

The reductant pump plays a crucial role in the SCR system by precisely injecting DEF into the exhaust stream. An open circuit in its control system can prevent proper DEF delivery, leading to increased emissions and potential engine performance issues.

Common Causes

Several factors can trigger the P20FA code:

1. Faulty reductant pump
2. Damaged or corroded wiring in the pump control circuit
3. Loose or disconnected electrical connectors
4. Failed PCM (rare)
5. DEF quality issues or contamination
6. Blown fuse in the reductant pump circuit

Both electrical and mechanical issues can contribute to this fault. Electrical problems like wiring breaks or connector faults are common, while mechanical failures of the pump itself can also trigger this code.

Diagnostic Procedure

To diagnose the P20FA code, follow these steps:

1. Connect an OBD-II scanner and confirm the P20FA code.
2. Check for any additional codes that may be related.
3. Inspect the DEF tank level and quality.
4. Visually inspect all wiring and connectors related to the reductant pump.
5. Test the reductant pump's electrical resistance and compare to specifications.
6. Check the voltage supply to the pump when commanded on by the PCM.
7. Perform a circuit continuity test between the PCM and the reductant pump.
8. If all else checks out, consider testing the PCM outputs.

Required tools: OBD-II scanner, digital multimeter, wiring diagrams, and possibly a specialized SCR system tester.

Solutions

Depending on the diagnosis, solutions may include:

1. Repairing or replacing damaged wiring
2. Replacing corroded or loose connectors
3. Replacing the faulty reductant pump
4. Updating PCM software if available
5. In rare cases, replacing the PCM

Always refer to the vehicle's service manual for specific repair procedures and torque specifications.

Prevention

To prevent P20FA and related issues:

1. Use high-quality DEF and keep the tank filled
2. Perform regular maintenance on the SCR system
3. Protect wiring and connectors from corrosion and physical damage
4. Address any DEF-related warning lights promptly

Cost Analysis

Repair costs can vary significantly based on the root cause:

• Wiring repair: $100-$300 (€90-€270)
• Reductant pump replacement: $500-$1000 (€450-€900)
• PCM replacement and programming: $1000-$2000 (€900-€1800)

Labor costs typically range from $100-$200 (€90-€180) per hour.

Related Issues

P20FA often occurs alongside other SCR system codes such as:

• P20EE: SCR NOx Catalyst Efficiency Below Threshold
• P204F: Reductant System Performance
• P203F: Reductant Level Sensor Circuit Range/Performance

These codes may indicate broader issues with the SCR system that should be addressed comprehensively.

By understanding the P20FA code and its implications, engineers and mechanics can effectively diagnose and repair issues with diesel SCR systems, ensuring optimal performance and emissions control.

P20FA Diagnostic Trouble Code FAQ

What does the P20FA code mean?

P20FA indicates a Reductant Pump ‘B’ Control Circuit/Open issue in the vehicle’s Selective Catalytic Reduction (SCR) system.

How serious is the P20FA code?

This code is considered critical and can lead to damage if not addressed promptly. It’s recommended to have the vehicle inspected as soon as possible.

Is it safe to continue driving with a P20FA code?

It’s not recommended to continue driving, as it may cause damage to the SCR system and lead to reduced engine performance or shutdown.

What components are involved in a P20FA code?

The main components involved are the reductant pump ‘B’, its control circuit, the Powertrain Control Module (PCM), and the SCR system.

Is P20FA a generic or manufacturer-specific code?

P20FA is a generic powertrain code related to the vehicle’s emissions control system.

What are common causes of the P20FA code?

Common causes include a faulty reductant pump, damaged wiring, loose connectors, PCM issues, or DEF quality problems.

How is the P20FA code diagnosed?

Diagnosis involves using an OBD-II scanner, inspecting wiring and connectors, testing the reductant pump’s electrical resistance, and checking voltage supply and circuit continuity.

What tools are needed to diagnose P20FA?

Required tools include an OBD-II scanner, digital multimeter, wiring diagrams, and possibly a specialized SCR system tester.

Can P20FA be fixed at home?

While some repairs might be possible for skilled mechanics, it’s generally recommended to have a professional diagnose and repair this issue due to its complexity.

What are potential repairs for P20FA?

Repairs may include replacing damaged wiring, connectors, or the reductant pump, updating PCM software, or in rare cases, replacing the PCM.

How much does it typically cost to repair a P20FA issue?

Repair costs can range from $100-$2000 (€90-€1800) depending on the root cause and required repairs.

Can P20FA affect fuel economy?

Yes, a malfunctioning SCR system can potentially impact fuel economy and engine performance.

Will P20FA cause the Check Engine Light to come on?

Yes, P20FA will typically trigger the Check Engine Light or a specific DEF system warning light.

Are there any preventive measures to avoid P20FA?

Regular maintenance of the SCR system, using high-quality DEF, and addressing warning lights promptly can help prevent P20FA.

Can low-quality DEF cause P20FA?

While low-quality DEF is not a direct cause of P20FA, it can contribute to SCR system issues that may lead to this code.

What other codes are often associated with P20FA?

Related codes may include P20EE, P204F, and P203F, which are also associated with SCR system issues.

Does P20FA affect emissions?

Yes, since P20FA indicates an issue with the SCR system, it can potentially lead to increased emissions if not addressed.

Can extreme weather conditions trigger P20FA?

While not a direct cause, extreme cold can affect DEF and potentially contribute to SCR system issues.

How long does it typically take to repair a P20FA issue?

Repair time can vary from 1-4 hours depending on the root cause and required repairs.

Will P20FA clear itself?

It’s unlikely that P20FA will clear itself without addressing the underlying issue. Even if the code disappears temporarily, it will likely return if the problem persists.