Fix P20BA: Mechanic’s solutions that WORKED

The code P20BA: Reductant Heater ‘A’ Control Circuit Performance points to an issue in the ‘A’ control circuit of the reductant heater, a key component in the vehicle’s Diesel Exhaust Fluid (DEF) system. This heater is crucial for maintaining the DEF fluid at proper temperatures, essential for reducing harmful emissions. Malfunctions in this circuit can lead to increased emissions and reduced engine performance.

P20BA quick overview

Meaning	P20BA: Reductant Heater ‘A’ Control Circuit Performance
Is it serious?	This code is serious as it affects the vehicle’s emissions control system, potentially leading to reduced engine performance and increased emissions.
Possible causes	– Faulty reductant heater in the DEF (Diesel Exhaust Fluid) system – Wiring or electrical connector issues in the reductant heater circuit – DEF tank or heater assembly malfunction – Diesel contamination in the DEF fluid
How to diagnose?	Inspect Reductant Heater: Check the reductant heater for any signs of malfunction or damage. Evaluate Electrical Connections: Examine wiring and connectors related to the reductant heater circuit for any faults. Check DEF Fluid and Tank: Ensure the DEF fluid is not contaminated and the tank is functioning correctly. Assess Heater Assembly: Inspect the entire heater assembly in the DEF system for defects. Replace if Necessary: Consider replacing the reductant heater or assembly if found faulty.

How to fix P20BA – learn from mechanics

I looked into P20BA service cases at iatn.com website where in the private forums the mechanics seek advice from other mechanics. I looked up a bunch of cases to help you decide how to fix your issue and see what would a real mechanic do to solve it.

Case #1: Ford

Vehicle Information: 2015 Ford F-350 Super Duty Lariat 6.7L

Issue + Repair History:

• MIL Lamp on with only code P20BA.
• The heater resistance measured at 3.2 ohms, slightly above the specification of 1-2.5 ohms.

Other OBD2 Codes + Test Results: P20BA – Reductant Heater A Control Performance

Suggestions to Fix Issue:

• Replace the heater as the resistance being out of specification can trigger the code.
• Consider resistance as a percentage of specification.
• Check all connector crimps, related grounds, and relay part numbers.
• Use tools like a load pro for effective troubleshooting.

Final Fix: The issue was resolved by replacing the reductant heater. The new heater had a resistance of 2 ohms, within the specified range, which fixed the problem.

Case #2: Ford

Vehicle Information: 2011 Ford F-350 Super Duty King Ranch 6.7L

Issue + Repair History:

• MIL Lamp on with reported occasional lack of power.
• Presented codes: P20BA, P0E8, and P0B9.

Other OBD2 Codes + Test Results:

• P20BA – Reductant Heater A Control Performance
• P0E8 – Reductant Pressure Too Low
• P0B9 – Heater A Control Circuit Open

Suggestions to Fix Issue:

• Check the resistance and circuit of Heater A.
• Consider possible DEF/urea system issues, including accidental diesel top-off in DEF tank.
• Lower DEF tank to check power, grounds, and heater circuit resistance.
• Replace DEF tank heater if resistance tests indicate failure.
• Check for DEF pump pressure in the reductant system.
• Verify DEF fluid level and check for diesel contamination in the tank.

Final Fix: The issue was resolved by replacing the DEF heater sender assembly, which led to the truck running better with no more codes.

Case #3: Ford

Vehicle Information: 2011 Ford F-550 Super Duty XL 6.7L

Issue + Repair History:

• Vehicle stalled twice going uphill, with MIL Lamp on and code P0093 (fuel system leak).
• Previous issue within 4000 km, resolved with fuel filter replacement.
• Under load, fuel pressure drops to 56 PSI but still accelerates slowly.
• No problems on flat roads.

Other OBD2 Codes + Test Results:

• P0093 – Fuel system leak detected-Large leak
• P0673 – Cyl 3 glow plug circuit
• P20BA – Reductant heater control performance
• Fuel pressure at 56 PSI under load, 62 PSI at idle.

Suggestions to Fix Issue:

• Check for air in fuel supply and return lines.
• Verify if there’s fuel contamination in the oil.
• Pressure test turbo and intake hoses.
• Inspect the fuel volume control valve and other related sensors.
• Assess low and high-pressure fuel pump functionality.

Final Fix: The Ford dealer resolved the issue by replacing the fuel pressure regulator (FPCV) on the rear of the left-hand fuel rail. The FPCV was leaking under high pressure, dropping the actual fuel pressure and setting codes P0093 or P0087. The fuel volume control valve (VCV) on the high-pressure pump was also checked. An additional test involved checking for leakage from a disconnected return connector at the rear of the fuel rail.

Common Advice	Description of Diagnostic Step
Replace DEF Heater or Assembly	If DEF heater or its assembly shows resistance out of specification or other malfunctions, consider replacement.
Check Fuel Pressure and Filters	Monitor fuel pressure under various conditions and replace fuel filters if necessary.
Inspect Fuel System Components	Evaluate fuel pressure regulator, volume control valve, and related components for leaks or malfunctions.
Check for Fuel Contamination	Ensure there is no diesel contamination in DEF tank or fuel in the oil, indicating system issues.
Perform Electrical Checks	Examine wiring and electrical connections related to the fuel and DEF systems for faults.