Fix P219B: Mechanic’s solutions that WORKED

The code P219B: Bank 2 Air/Fuel Ratio Imbalance indicates a problem with the mixture of air and fuel being burned in the engine’s second bank of cylinders. This imbalance can be caused by a variety of issues ranging from vacuum leaks to faulty sensors.

P219B quick overview

Meaning	P219B: Bank 2 Air/Fuel Ratio Imbalance
Is it serious?	Yes, it can be serious as it may lead to poor engine performance, increased emissions, and potential damage to the catalytic converter.
Possible causes	– Vacuum leaks – Faulty fuel injectors – Clogged fuel filter – Malfunctioning oxygen sensors – Exhaust leaks – Faulty Mass Air Flow (MAF) sensor – Fuel pressure issues – Contaminated or poor-quality fuel – Engine timing issues – Worn spark plugs or ignition coils
How to diagnose?	1. Read the freeze frame data and check for any additional codes. 2. Inspect for any obvious signs of damage or leaks in the intake and exhaust systems. 3. Test fuel quality and pressure to ensure proper delivery to the engine. 4. Check the operation of the oxygen sensors and MAF sensor. 5. Examine spark plugs and ignition coils for wear or damage. 6. Perform a vacuum leak test to identify any air leaks. 7. Evaluate engine timing and valve clearances, if applicable. 8. Consider a professional diagnostic tool to monitor real-time data and pinpoint the issue.

In simple terms, the P219B code means that the engine is not mixing the right amount of air with the fuel before it burns it. This can make the engine run poorly and cause other problems. It’s like a recipe that has too much or too little of an ingredient, which can spoil the dish.

How to fix P219B – learn from mechanics

I looked into P219B 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: Chevrolet

Vehicle Information 2014 Chevrolet Express 1500 4.3L

Issue + Repair History

• MIL (Malfunction Indicator Lamp) on
• Codes: P219B (fuel trim cylinder balance bank 2), P2273 (B2S2 O2 sensor stuck rich)
• Replaced spark plugs, wires, and downstream O2 sensor
• No history or present misfire counters, fuel trims in range

Other OBD2 Codes + Test Results

• P219B: Fuel trim cylinder balance bank 2
• P2273: B2S2 O2 sensor stuck rich

What Are People Suggesting to Fix Issue

• Check injectors, perform injector drop test
• Swap front HO2S sensors to see if code follows
• Check for exhaust leaks before the front O2 sensor
• Check fuel pressure, volume, and quality
• Perform a fuel trim reset
• Check for partially plugged converter
• Monitor for current misfires on a cold start

What Was the Final Fix

• Replaced injectors as suggested by the community

Case #2: Chevrolet

Vehicle Information 2011 Chevrolet Silverado 1500 LT 4.8L

Issue + Repair History

• Codes: P0300 (misfire), P0219B (fuel trim cylinder balance bank 2)
• Multiple misfires, mainly on cylinder #6, random on cylinders 3 and 4
• Fuel trim, O2 sensors, fuel injector test, compression test, coil packs, wires, plugs, and intake spray test all checked good
• Truck idles fine

What Are People Suggesting to Fix Issue

• Check for roller lifter or cam pitting
• Check operation of Active Fuel Management (AFM) system
• Inspect freeze frame data, coolant temperature, spark plugs for carbon tracking, and front oxygen sensors
• Perform a running compression test
• Check for exhaust leaks near the cylinder
• Pull oil filter and check for metals, drop oil pan for MDS failure
• Check mode 06 for any failures in monitors
• Fresh fuel, clean injectors
• Use Seafoam as a potential quick fix
• Ensure correct oil and filter are used, check oil pressure cold and hot
• Watch misfire data on a cold start with a scan tool

What Was the Final Fix

• Replaced injectors #6 and #1 after noticing a small drop in the #6 injector during a morning test

Case #3: Nissan

Vehicle Information 2016 Nissan Titan XD S 5.6L

Issue + Repair History

• Running very rough, multiple codes present
• Codes: P219a, P219b (Air-Fuel Ratio Imbalance), P0011, P0021, P0014, P0024 (Camshaft Position Timing Over-Advance), P0305, P0304, P0303 (Misfires), P1197 (Fuel Run Out)
• Plugs changed 400 miles ago, didn’t fix the issue
• Fuel pressure erratic, improved with carb cleaner introduction
• Fuel sample appeared fine
• Vehicle sent to Nissan for timing issues

Other Test Results

• Low Side Fuel Pressure: 52 psi, erratic
• Spark: Present
• Plugs: Dark
• Fuel: Appears good

What Are People Suggesting to Fix Issue

• Check oil level
• Test for ethanol percentage in fuel
• Pay for a subscription to Nissan for a diagram, check CAN connections
• Check for erratic fuel pressure as a starting point
• Consider timing chain issues, check compression
• Hot oil pressure check for VVT operation
• Check for cam advance PIDs, actual vs desired
• Refer to TSB for P219A and P219B, don’t replace A/F sensor
• Check lifter below high-pressure fuel pump
• Pull VVT solenoids and check screens, check fuel trims and AFR sensors

What Was the Final Fix

• Left front converter came apart and plugged the second converter, replaced converters
• Oil was thick and sludgy, replaced oil
• Vehicle still ran rough, sent to Nissan for timing issues

Case #4: Ford

Vehicle Information 2015 Ford F-550 Super Duty XL 6.8L

Issue + Repair History

• Surge under acceleration after catalytic converter replacement
• Replaced parts: fuel pump, fuel pump module, mass air flow sensor, both upstream air fuel ratio sensors, Ford OE catalytic converter, Bank 2 fuel injectors
• Engine replaced a year ago with a Ford reman
• Equivalence air fuel ratio PID for bank 1 and 2 fluctuating significantly
• Adding propane while driving corrects the issue
• Unplugging both upstream air fuel ratio sensors corrects the issue
• KAM reset temporarily fixes the issue for about 20 miles

Final Fix

• Replaced the rear O2 sensor, vehicle now runs great

Computer Codes & Descriptions

• P0420: Catalyst System Efficiency Below Threshold (Bank 1)
• P219A: Bank 1 Air/Fuel Ratio Imbalance
• P219B: Bank 2 Air/Fuel Ratio Imbalance

Suggestions from Others

• Check PCM for dropping a reference voltage circuit
• Perform vacuum gauge reading and compression test
• Check for global vacuum leak or fuel starvation
• Inspect spark plugs
• Check coils for low output
• Change the fuel filter, especially the secondary
• Perform a scope test on the fuel pump for a clean ripple pattern
• Pressure and volume test for the fuel pump
• Take a fuel sample for contamination

Additional Comments

• Concerns were raised about the rear O2 sensor not typically factoring into fuel control and the possibility of the issue returning.

Case #5: Honda

Vehicle Information 2016 Honda Pilot EX 3.5L

Issue + Repair History

• Running rough with multiple dashboard lights on
• Misfires under acceleration after injector replacement and PGM update
• Misfires on all cylinders without setting any faults
• New spark plugs installed
• One new ignition coil tested without improvement
• Fuel tested with 10% alcohol
• High pressure fuel reading between 500psi and 2000psi
• Low side fuel pressure within spec (60-65psi)
• Fuel trims at -5% to -10% from idle to cruising

Final Fix

• Shaking due to torque converter clutch lock up (found a bulletin for this)
• Misfires detected by the tool were not considered out of the ordinary by the car (no faults set and all OBD II readiness set)
• Vehicle released to the customer

Computer Codes & Descriptions

• P0300: Misfires, also misfires on all cylinders
• P219A: Bank 1 air-fuel ratio imbalance
• P219B: Bank 2 air-fuel ratio imbalance
• P0430: Catalyst system efficiency below threshold bank 2

Suggestions from Others

• Check MAP voltage and/or valve tappet clearance
• Check back pressure
• Check valve clearance, especially for exhaust valves
• Check for possible incorrect installation of the gasket for the top plate of the intake plenum
• Check fuel supply, pressure, and volume
• Consider the possibility of E-85 fuel
• Look at fuel trim numbers and MAF reading at WOT
• Consider bad gas or timing chain issues
• Replace O2 sensors and/or address MAF if needed
• Check for partially clogged catalytic converter

Additional Comments

• The misfires and catalyst inefficiency were symptoms of the air/fuel ratio imbalance codes
• The shaking was unrelated to the misfires and was due to the torque converter clutch lock up
• The vehicle was not setting any faults despite the misfires detected by the scan tool

Advice	Brief Description of Diagnostic Step
Check Fuel Quality	Test for ethanol percentage and overall fuel quality to rule out fuel-related issues.
Inspect Fuel Pressure	Measure both low and high side fuel pressures to ensure they are within specifications.
Evaluate Fuel Trims	Analyze fuel trim data at idle and under load to assess if the engine is running rich or lean.
Check for Vacuum Leaks	Inspect for any vacuum leaks that could cause air-fuel ratio imbalances.
Inspect Spark Plugs	Examine spark plugs for signs of fouling or damage that could contribute to misfires.
Test Ignition Coils	Evaluate ignition coils for proper operation as faulty coils can lead to misfires.
Check Valve Clearances	Especially in Honda engines, tight or incorrect valve clearances can cause misfires.
Examine Exhaust Back Pressure	High back pressure can indicate a clogged catalytic converter, leading to misfires.
Consider O2 Sensors	Faulty oxygen sensors can provide incorrect data, leading to air-fuel ratio imbalances.
Check for Software Updates	Ensure the vehicle’s software is up to date, as updates can resolve certain misfire issues.
Perform a KAM Reset	Resetting the Keep Alive Memory can sometimes temporarily resolve misfire issues.
Inspect Intake Manifold Gaskets	Incorrectly installed gaskets can cause air leaks and misfires.
Evaluate MAF Sensor	A faulty Mass Air Flow sensor can cause incorrect air-fuel ratio readings.
Check for Timing Issues	Incorrect timing, often due to a stretched timing chain, can lead to misfires.
Consider Professional Diagnosis	If basic checks don’t resolve the issue, a more in-depth professional diagnosis may be necessary.