P20FF – Reductant Quality Sensor Circuit High

What is P20FF?

P20FF is a manufacturer-specific powertrain diagnostic trouble code (DTC) that indicates a problem with the reductant control module performance. This code is commonly seen on diesel vehicles equipped with a Selective Catalytic Reduction (SCR) system to reduce NOx emissions. When this code is triggered, it means the engine control module (ECM) has detected an issue with the reductant control module, which manages the injection of diesel exhaust fluid (DEF) into the exhaust stream.

Urgency and Driving with P20FF

If your vehicle is displaying the P20FF code, it's best to address it promptly. While it may be possible to continue driving for a short period, ignoring this code can lead to further damage to the emissions system and potentially cause the vehicle to enter a "limp mode" with reduced power. It's advisable to have the issue diagnosed by a qualified mechanic or visit a dealership as soon as possible.

Is P20FF a General Code?

P20FF is a manufacturer-specific code, meaning its exact definition may vary between different vehicle makes and models. However, it generally relates to a problem with the reductant control module in diesel vehicles with SCR systems. Some common vehicles that may encounter this code include certain Nissan Navara, Chevrolet, and BMW models.

Parts Involved and Their Roles

The main components involved when the P20FF code is triggered are:

1. Reductant Control Module: This module controls the injection of DEF into the exhaust stream to reduce NOx emissions. It communicates with the ECM to ensure the proper amount of DEF is injected based on engine operating conditions.

2. Diesel Exhaust Fluid (DEF) Injector: The DEF injector is responsible for spraying a fine mist of DEF into the exhaust stream before it reaches the SCR catalyst.

3. Selective Catalytic Reduction (SCR) Catalyst: The SCR catalyst is a honeycomb-like structure coated with precious metals that convert NOx into harmless nitrogen and water when exposed to DEF.

Common Causes

Some common causes of the P20FF code include:

• Faulty reductant control module
• Damaged or clogged DEF injector
• Low or contaminated DEF fluid
• Wiring issues between the reductant control module and ECM
• Exhaust leaks before the SCR catalyst

Diagnosing P20FF

To properly diagnose the P20FF code, follow these steps:

1. Connect an OBD-II scanner and retrieve the stored fault codes.
2. Check the DEF level and quality. If the fluid is low or contaminated, refill or replace it as necessary.
3. Inspect the wiring and connectors between the reductant control module and ECM for any damage or loose connections.
4. Check for exhaust leaks before the SCR catalyst using a smoke machine or visual inspection.
5. If no other issues are found, the reductant control module may need to be replaced.

Solutions and Repair Costs

The solution for the P20FF code will depend on the root cause identified during diagnosis. Some potential fixes and their estimated costs include:

• Replacing the reductant control module: $500-$1,000 (€450-€900)
• Replacing the DEF injector: $300-$600 (€270-€540)
• Refilling or replacing contaminated DEF fluid: $20-$50 (€18-€45) for 2.5-10 gallons (9.5-38 liters)
• Repairing wiring issues: $100-$300 (€90-€270)
• Fixing exhaust leaks: $100-$500 (€90-€450) depending on location and severity

Prevention

To prevent the P20FF code from occurring, follow these tips:

• Regularly maintain your vehicle according to the manufacturer's recommended schedule.
• Use high-quality DEF fluid that meets ISO 22241 standards.
• Avoid running the DEF tank empty, as this can damage the DEF injector and reductant control module.
• Address any exhaust leaks promptly to prevent damage to the SCR system.

Related Fault Codes

Some other fault codes that may appear alongside P20FF include:

• P20EE: SCR NOx Catalyst Efficiency Below Threshold
• P249D: Reductant Injection Valve Performance
• P249E: Reductant Injection Valve Stuck
• P226D: Reductant Quality Performance

By understanding the P20FF code, its causes, and potential solutions, you can quickly address this issue and keep your vehicle's emissions system functioning properly. Always consult with a qualified mechanic if you are unsure about any aspect of the diagnosis or repair process.

Frequently Asked Questions About P20FF

What does the OBD-II code P20FF mean?

P20FF is a manufacturer-specific powertrain diagnostic trouble code that indicates a problem with the reductant control module performance. This code is commonly seen on diesel vehicles equipped with a Selective Catalytic Reduction (SCR) system to reduce NOx emissions.

Which vehicle components are involved with P20FF?

The main components involved when P20FF is triggered are:
1) Reductant control module
2) Diesel exhaust fluid (DEF) injector
3) Selective catalytic reduction (SCR) catalyst

What are the common causes of code P20FF?

Common causes include a faulty reductant control module, damaged/clogged DEF injector, low/contaminated DEF fluid, wiring issues between the reductant control module and engine control module (ECM), and exhaust leaks before the SCR catalyst.

How serious is the P20FF code? Is it safe to keep driving?

While it may be possible to continue driving for a short period, it’s best to address P20FF promptly. Ignoring it can lead to further damage to the emissions system and potentially cause reduced engine power. Have the issue diagnosed as soon as possible.

Is code P20FF specific to certain makes and models?

P20FF is manufacturer-specific, so its exact definition may vary between vehicle makes/models. However, it generally indicates a reductant control module issue on diesel vehicles with SCR systems. It has been reported on some Nissan Navara, Chevrolet, and BMW models.

How do you diagnose the root cause of code P20FF?

Diagnosis steps include:
1) Scan for codes
2) Check DEF level and quality
3) Inspect wiring and connectors
4) Check for exhaust leaks
5) Test the reductant control module

Can low or contaminated DEF fluid cause the P20FF code?

Yes, low DEF fluid levels or contaminated/diluted DEF can trigger the P20FF code. The reductant control module monitors DEF quality.

What are the typical repair costs associated with P20FF?

Repair costs depend on the root cause. Potential costs range from $20-$50 for a DEF refill to $500-$1000+ for a reductant control module or DEF injector replacement. Wiring repairs and exhaust leak fixes fall in between.

Can a clogged DEF injector cause code P20FF?

Yes, a clogged or damaged DEF injector can trigger the P20FF code by restricting DEF flow into the exhaust stream. The reductant control module detects this as a system malfunction.

How often should the DEF tank be refilled to avoid P20FF?

DEF tanks should be refilled periodically as part of routine maintenance, typically every oil change or 5,000-10,000 miles. Avoid running the DEF tank empty, as this can damage components and trigger codes like P20FF.

What are some other common codes that may appear with P20FF?

Related codes that may appear alongside P20FF include:

• P20EE (SCR NOx catalyst efficiency low)
• P249D (Reductant injection valve performance)
• P249E (Reductant injection valve stuck)
• P226D (Reductant quality performance)

Can a faulty NOx sensor cause the P20FF code?

While a failing NOx sensor can cause other SCR system codes, it would not directly trigger P20FF. This code is more related to DEF delivery issues than NOx sensor readings. However, multiple SCR codes may appear together.

How do you test the reductant control module?

Testing the reductant control module typically involves checking for power, ground, and proper communication with the ECM. Consult the factory service information for the specific testing procedures for your vehicle.

Can exhaust leaks cause the P20FF code?

Yes, exhaust leaks upstream of the SCR catalyst can allow oxygen to enter the exhaust stream, affecting DEF injection and SCR efficiency. The reductant control module may detect this as a system fault and trigger P20FF.

Is it necessary to use OEM parts for P20FF repairs?

While aftermarket parts may be less expensive, it’s generally recommended to use OEM components for critical emissions systems like the SCR. Consult with a qualified mechanic to determine the best repair path for your specific vehicle.

How do you check DEF quality?

DEF quality can be checked using a refractometer to measure the urea concentration. The acceptable range is 31.8-33.2%. Contaminated or diluted DEF should be replaced.

Can a weak battery cause the P20FF code?

While a weak battery itself wouldn’t trigger P20FF, low voltage could potentially cause issues with the reductant control module or associated sensors and solenoids. Ensuring a properly charged battery is important for overall system operation.

What is the ISO 22241 standard mentioned for DEF?

ISO 22241 is the international standard that specifies the quality requirements for DEF/AdBlue used in SCR systems. Using DEF that meets this standard helps ensure proper system performance and minimizes issues like P20FF.

How does the reductant control module differ from the ECM?

The reductant control module is a separate controller that specifically manages the DEF injection and SCR system. It communicates with the main ECM but has its own dedicated functions.

Can P20FF cause the engine to shut down while driving?

In most cases, P20FF itself would not cause an immediate engine shutdown. However, if the code persists and the SCR system performance degrades significantly, the vehicle may enter a “limp mode” with reduced power to protect the engine and emissions components. Address the code promptly to avoid further issues.