Fix P219A: Mechanic’s solutions that WORKED

The code P219A indicates a “Bank 1 Air/Fuel Ratio Imbalance” in the vehicle’s engine. While not an extremely critical issue, it should be addressed to maintain optimal performance and emissions.

This code often results from various factors, including fuel quality, vacuum leaks, injector problems, mechanical issues, software updates, compression variations, O2 sensor malfunctions, or multi-air system concerns. To diagnose and resolve this code, a series of steps can be taken to identify the underlying cause.

P219A quick overview

Meaning	P219A – Bank 1 Air/Fuel Ratio Imbalance
Is it serious?	Moderate
Possible causes	– Fuel quality issues, such as high alcohol content or contamination – Vacuum leaks in the intake tract – Injector balance problems – Mechanical issues, including worn cam lobes or rockers – PCM software updates or reflash – Compression disparities in the engine – O2 sensor malfunctions – Issues with the multi-air system
How to diagnose?	Check for software updates or PCM reflash to ensure the vehicle’s software is current. Perform an injector balance test to verify even fuel delivery across cylinders. Examine the intake tract for vacuum leaks using a smoke machine or other diagnostic methods. Inspect valve train components, including lifters, rockers, valve springs, and valve timing, for signs of wear or malfunction. Conduct a compression test to measure and compare compression levels in each cylinder. Use an oscilloscope to scope the O2 sensor against ignition events to identify the problematic cylinder. Test fuel quality for contaminants or incorrect alcohol content, especially if the vehicle is not designed for higher ethanol blends. Investigate mechanical issues such as worn cam lobes or rockers that could affect engine performance. Consult with manufacturer support or resources like the STAR center for guidance on uncommon or persistent issues. Consider performing a combustion area cleaning as a potential resolution, as seen in some cases.

How to fix P219A – learn from mechanics

I looked into P219A 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: Honda

Vehicle Information 2016 Honda Fit EX-L 1.5L

Issue + Repair History

• MIL with code P219A (Air fuel ratio imbalance between cylinders)
• Replaced injectors, supply pipe, and spark plugs

Other OBD2 Codes + Test Results

• No additional codes mentioned

What Are People Suggesting to Fix Issue

• Change the engine oil in case it has fuel in it
• Replace all 4 new fuel injectors and the fuel rail due to a known Honda defect
• Check if the vehicle is still under warranty
• Perform a PCM reset and idle relearn, then check short term fuel trims
• Ensure clean oil and no carbon buildup issues
• Check for exhaust or intake leaks
• Change oil and engine oil filter, and check the fuel quality

What Was the Final Fix

• The replacement of injectors, pipe, and spark plugs fixed the problem. Fuel trims looked great after 50 miles of driving. The injector test was found to be unreliable.

Case #2: Chevrolet

Vehicle Information 2013 Chevrolet Silverado 1500 WT 4.3L

Issue + Repair History

• MIL with codes P0716, P0717 (transmission input sensor issues), and P219A (fuel trim cylinder balance bank 1)
• Wiring checked from the trans computer to the transmission
• Issue persists after driving for about 20 minutes

What Are People Suggesting to Fix Issue

• Check if the vehicle is still under warranty
• Check 15A fuse #19 (trans ig1) in the underhood fuse box
• Check TCM data output concerning ISS (Input Speed Sensor)
• Consider that it might be an input speed sensor shorting out intermittently

What Was the Final Fix

• Replaced the input shaft sensor, which was behind the front pump. There was a service bulletin for this code indicating the sensor could be the issue.

Case #3: GMC

Vehicle Information 2013 GMC Yukon XL 1500 SLT 5.3L

Issue + Repair History

• MIL with code P219A (fuel trim cylinder balance bank 1)
• Engine replaced 5,000 miles ago due to issues with cylinder disable function
• Replacement engine installed, but code P219A reappeared within 200 miles

What Are People Suggesting to Fix Issue

• Check fuel trims and alcohol content
• Compare O2 sensor readings between banks
• Check for vacuum leaks or injector issues
• Consider non-OEM O2 sensor or exhaust/intake modifications as potential causes
• Suggested swapping O2 sensors side to side to see if the code changes
• Possible intake or exhaust valve leak

What Was the Final Fix

• The issue was base oil pressure below specification due to internal engine issues, causing hesitation in re-enabling disabled cylinders. Another engine was installed along with DOD (Displacement on Demand) delete programming, resolving the issue.

Case #4: Chrysler

Vehicle Information 2014 Chrysler Town & Country Touring 3.6L

Issue + Repair History

• Hesitation and engine tick
• MIL with code P219A (Bank 1 air-fuel ratio imbalance)
• Suspected ticking from a rocker arm
• Lifter noise identified, cam lobe also worn, requiring cam replacement

What Are People Suggesting to Fix Issue

• Test injectors for pressure drop and smoke the intake tract for leaks
• Check for damaged cam lobes, particularly the intake cams
• Perform a relative compression test to identify high compression due to intake cam and rocker wear
• Conduct an injector balance test and spark test for ignition problems
• Inspect valve covers and oil for metal debris

What Was the Final Fix

• The noise was coming from a lifter, and the cam lobe was also worn. Both the lifter and cam were replaced to fix the problem.

Case #5: Jeep

Vehicle Information 2017 Other Chrysler Cherokee 2.4L

Issue + Repair History

• MIL with code P219A (Bank 1 air/fuel ratio imbalance)
• Jeep runs well hot and cold, no misfires
• Compression test and cylinder leakage test showed normal results
• Upstream O2 sensor replaced, but issue persisted
• PCM update performed, but code returned
• STAR center suggested replacing injectors, which was done
• Combustion area cleaning with Chrysler cleaner was the last action taken before the code ceased to return

Suggestions from Others

• Check fuel quality, particularly alcohol content
• Check for software updates or reflash to correct emission fault
• Perform injector balance test
• Check for vacuum leaks, possibly using a high-pressure smoke machine
• Inspect valve train, lifters, rockers, valve springs, valve timing, and the multiair system
• Scope shot of the O2 sensor against ignition to identify the problematic cylinder

What Was the Final Fix

• The last action taken was a combustion area cleaning with Chrysler cleaner, after which the code did not return. The vehicle has been gone for over a week without the code reappearing.

Advice	Brief Description of Diagnostic Step
Check for software updates or PCM reflash	Ensure the vehicle’s software is up-to-date as this can sometimes resolve the issue.
Perform injector balance test	Test the injectors to ensure they are delivering fuel evenly across all cylinders.
Check for vacuum leaks	Use a smoke machine or other methods to detect any leaks in the intake tract that could affect air/fuel ratio.
Inspect valve train components	Examine lifters, rockers, valve springs, and valve timing for any signs of wear or malfunction.
Conduct a compression test	Measure the compression in each cylinder to identify any discrepancies that could indicate engine issues.
Scope O2 sensor against ignition	Use an oscilloscope to compare the O2 sensor readings against the ignition events to pinpoint the problematic cylinder.
Check fuel quality	Test the fuel for contaminants or incorrect alcohol content, especially if the vehicle is not designed for higher ethanol blends.
Consider mechanical issues	Look into potential mechanical faults such as worn cam lobes or rockers that could affect engine performance.
Consult with manufacturer support	If available, use resources like the STAR center for guidance on uncommon or persistent issues.
Perform combustion area cleaning	Clean the combustion area, which in some cases has resolved the issue without further action.