P20B8 - Understanding DTC P20B8: Common in 2015-2018 Ford Diesel Models

Quick Answer

P20B8 means: P20B8 indicates a malfunction in the reductant dosing control module in your vehicle's SCR system.

Fix: Check and replace faulty components Cost: $300 - $800 Time: 90-180 minutes

Can I drive with P20B8? Immediate attention is recommended to prevent emission issues and engine performance problems.

Common Questions

What does P20B8 mean and how does it affect my car?

The P20B8 code indicates a malfunction in the reductant dosing control module, which is critical for reducing emissions in diesel vehicles. This can lead to poor engine performance, increased emissions, and potential compliance issues during inspections.

What are the most common causes of P20B8 and how much does it cost to fix?

Common causes include a faulty reductant dosing control module and low DEF levels. Repair costs can range from $100 for wiring fixes to $800 for module replacements, depending on the issue.

Can I drive my car with P20B8 or should I stop immediately?

While you may still drive your vehicle, it is advisable to seek repairs as soon as possible to avoid further damage to the emissions system and to prevent the risk of failing emissions tests.

How can I diagnose P20B8 myself using GeekOBD APP?

Using the GeekOBD APP, you can start by scanning for error codes, reviewing the freeze frame data to understand the conditions that triggered the code, and checking the status of the reductant dosing control module.

What vehicles are most commonly affected by P20B8?

Vehicles such as the 2015-2018 Ford Super Duty models and similar diesel trucks frequently encounter the P20B8 code due to their SCR systems.

How can I prevent P20B8 from happening again?

Regularly check DEF levels, perform visual inspections of wiring and connectors, and ensure routine maintenance is conducted to keep the SCR system functioning properly.

What is P20B8?

DTC P20B8 refers to a diagnostic trouble code indicating an issue with the reductant system, specifically related to the dosing control module. This code typically arises in diesel-powered vehicles equipped with selective catalytic reduction (SCR) systems, which are designed to reduce harmful nitrogen oxides (NOx) emissions. In practical terms, a P20B8 code means that the engine control module (ECM) has detected a malfunction in the reductant dosing module, often due to issues such as incorrect fluid levels, sensor faults, or wiring problems. If you drive a 2015-2018 Ford Super Duty truck or similar models, you may encounter this code. Ignoring this code can lead to increased emissions, reduced performance, and potential damage to the SCR system. It’s crucial to address it promptly to maintain optimal vehicle function and comply with emission standards. A malfunctioning reductant system can severely impact your vehicle's ability to pass emissions tests, leading to costly repairs if left unchecked. Therefore, understanding and diagnosing the P20B8 code is essential for maintaining your diesel vehicle's performance and compliance.

System: P - Powertrain (Engine, Transmission, Emissions)

Symptoms

Common symptoms when P20B8 is present:

  • Check engine light illuminates and remains on, indicating a fault in the emissions system.
  • Engine may hesitate during acceleration, causing a noticeable delay in power delivery.
  • Fuel economy may decrease by 10-15%, leading to more frequent refueling and higher expenses.
  • Reduced engine performance, particularly under load, impacting towing and hauling capabilities.
  • Possible strong exhaust odor due to incomplete combustion and inefficient emissions control.

Possible Causes

Most common causes of P20B8 (ordered by frequency):

  1. The most common cause is a malfunctioning reductant dosing control module, which occurs in about 60% of cases due to wear or electrical failure.
  2. Another common cause is low or contaminated DEF (Diesel Exhaust Fluid) levels, which can lead to improper dosing and is often overlooked.
  3. Wiring issues, such as damaged or corroded connectors, can also trigger the P20B8 code. Regular inspections can help prevent this.
  4. Less common but serious causes include a faulty SCR catalyst, which can lead to severe emissions failures and require costly replacement.
  5. In rare cases, a defective ECM may cause false readings, necessitating recalibration or replacement of the control unit.

P20B8 Repair Costs

Cost Breakdown by Repair Type

Reductant Dosing Control Module Replacement

Replacing the faulty dosing control module to restore proper function to the SCR system.

  • Total: $300 - $800
  • Success rate: 95%
Wiring Repair or Replacement

Repairing or replacing damaged wiring and connectors to ensure proper electrical flow.

  • Total: $100 - $300
  • Success rate: 90%
Money-Saving Tips for P20B8
  • Start with the most common and least expensive repairs first
  • Use GeekOBD APP to confirm diagnosis before replacing expensive parts
  • Consider preventive maintenance to avoid future occurrences
  • Compare prices for OEM vs aftermarket parts based on your needs
  • Address the issue promptly to prevent more expensive secondary damage

Diagnostic Steps

Professional P20B8 Diagnosis Process

Follow these systematic steps to accurately diagnose P20B8. Each step builds on the previous one to ensure accurate diagnosis.

Step 1: Initial visual inspection - Check for obvious signs like damaged wiring, loose connections, or corrosion (5-10 minutes)
GeekOBD APP Tip: Use GeekOBD APP to monitor real-time data during this diagnostic step for accurate results and professional-grade analysis.
Step 2: OBD2 scan with GeekOBD APP - Retrieve all codes and freeze frame data to understand the fault context (10-15 minutes)
GeekOBD APP Tip: Use GeekOBD APP to monitor real-time data during this diagnostic step for accurate results and professional-grade analysis.
Step 3: Component testing - Use a multimeter or specific diagnostic tools to test the reductant dosing control module and related sensors (20-30 minutes)
GeekOBD APP Tip: Use GeekOBD APP to monitor real-time data during this diagnostic step for accurate results and professional-grade analysis.
Step 4: System function test - Verify proper operation after repairs and clear codes using the GeekOBD APP (10-15 minutes)
GeekOBD APP Tip: Use GeekOBD APP to monitor real-time data during this diagnostic step for accurate results and professional-grade analysis.
Step 5: Road test verification - Drive the vehicle under various conditions to confirm successful repair and check for any returning codes (15-20 minutes)
GeekOBD APP Tip: Use GeekOBD APP to monitor real-time data during this diagnostic step for accurate results and professional-grade analysis.

Important Notes

  • Always verify the repair with GeekOBD APP after completing diagnostic steps
  • Clear codes and test drive to ensure the problem is resolved
  • Address underlying causes to prevent code recurrence

Real Repair Case Studies

Case Study 1: P20B8 Diagnosis and Repair on a 2016 Ford F-250

Vehicle: 2016 Ford F-250, 85,000 miles

Problem: Customer noticed the check engine light was on and reported decreased towing performance.

Diagnosis: Diagnostic scan revealed P20B8. A visual inspection showed corroded wiring at the dosing control module.

Solution: Replaced the corroded wiring and the reductant dosing control module.

Cost: $750 (parts: $500, labor: $250)

Result: Check engine light cleared, towing performance restored, and passed emissions test.

Case Study 2: Wiring Issues Causing P20B8 on a 2017 Ford F-350

Vehicle: 2017 Ford F-350, 45,000 miles

Problem: Customer experienced engine hesitation and reduced fuel efficiency.

Diagnosis: P20B8 was confirmed. Follow-up revealed damaged wiring harness connections.

Solution: Repaired the wiring harness and performed a system reset.

Cost: $200 (parts: $50, labor: $150)

Result: Engine performance improved and fuel efficiency returned to normal.

Diagnose P20B8

Use GeekOBD APP for professional diagnosis!

  • Real-time data monitoring
  • Advanced diagnostic features
  • Step-by-step repair guidance
  • Professional-grade analysis
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Code Information

Code: P20B8
System: Powertrain (Engine, Transmission, Emissions)
Severity: HIGH
Category: Engine Codes