P219B Air-Fuel Ratio Cylinder Imbalance Bank 2

P219B Air-Fuel Ratio Cylinder Imbalance Bank 2 - the purpose of the cylinder imbalance detection monitor is to detect an air/fuel ratio imbalance between the cylinders across an entire cylinder bank. Athough it does not indicate as such, this fault will set because a specific cylinder on this bank is out of balance with the other cylinder. The fault may not be easily noticeable to the technician. During diagnosis, it is necessary to pay close attention to small differences between the cylinder during each of the test steps.

P219B Air-Fuel Ratio Cylinder Imbalance Bank 2


This imbalance can be caused by a number of different malfunctions including but not limited to:
  • Intake Manifold leak at a specific cylinder.
  • Fuel Injector problem.
  • Variable cam lift failure.
  • Camshaft/valvetrain problems.
  • Ignition system problems a specific cylinder.
  • Engine mechanical problems relating to cylinder combustion at a specific cylinder.
The cylinder imbalance detected requires that the Upstream O2 sensors are capable of operating at high frequencies, since an aged O2 sensors response capability at a higher frequency range can be degraded. Therefore, before this minitor come become active, the O2 sensor high frequency response monitor is performed to see if the sensor is even capable of detecting in imbalance.

Once active, the cylinder imbalance detection monitor matches up the upstream O2 sensor signal with the coressponding cylinder on the bank. Each cylinder is monitored and adjusments are made as needed for each cylinder to correct an air/fuel ratio imbalance. If an individual cylinder reaches a calibrated adaption threshold 15%), the diagnostic monitor will be considered failing.

When monitored:
  • Engine run time of 90 seconds.
  • Engine Coolant Temperature (ECT) is between 70°C -122°C (158°F -251°F).
  • Closed loop fuel control.
  • Engine speed between 1000-2700 rpm.
  • Calculated engine load between 30 - 90%.
  • The Upstream O2 sensor high frequency diagnostic monitor has run and passed this trip (indicate by P113D not being present).
  • For flex fuel vehicles the Fuel Adaptive learned must be completed.

Set conditions:
The Powertrain Control Module (PCM) detects that one of the cylinders on bank 2 has an air/fuel ratio imbalance of 15% when compared to the other cylinders on the same cylinder bank.

Default actions:
MIL is illuminated on the second consecutive trip that the diagnostic fails.

Possible causes:
  • Intake manifold leak at a specific cylinder on bank 2.
  • Fuel injector issues at a specific cylinder on bank 2.
  • Ignition  system issues at a specific cylinder on bank 2.
  • Cylinder compression imbalance.
  • Carbon build up.
  • Variable valve timing issues.
  • Valve train issues.

Diagnose code P219B Air-Fuel Ratio Cylinder Imbalance Bank 2

Step 1. Check for an active DTC
Start the engine, allow the engine to reach normal operating temperature. Test drive the vehicle in accordance with the when monitored conditions. With the scan tool, read DTC.

Is the DTC active or pending?

Yes, go to step 2.
No, perform the PCM intermittent condition.

Step 2. Check for an intake manifold leak at a specific cylinder on bank 2

Check for any of the following conditions, but not limited to:
  • Intake manifold seals leaking at a specific cylinder.
  • Intake plenum leak at a specific cylinder.
  • Warved/cracked intake manifold or plenum.
  • Vacuum leak at a fuel injector O-rings.

Were any issues found?

Yes, perform the appropriate repairs
No, go to step 3.

Step 3. Check for fuel injector issues at a specific cylinder on bank 2

Check for any of the following conditions, but not limited to:
  • Verify correct voltage supply at each fuel injector.
  • Verify correct control circuit operation at each fuel injector.
  • Verfiy correct fuel injector operation (spray pattern).

Were any issues found?

Yes, repair as necessary.
No, go to step 4.

Step 4. Check the cylinders on bank 2 for low compression and ignition system issues
Perform a cylinder compression and/or cylinder leak down test on each cylinder on bank 2.

Check the ignition system for any of the following conditions, but not limited to:
  • Verify correct voltage supply at each ignition coil.
  • Verify correct control circuit operation at each ignition coil.
  • Verify that the spark plugs are matching and are equivalent to OEM specifications.
  • Verify correct spark plug gap.
  • Visually inspect the ignition coils and spark plugs for signs of carbon tracking.
  • Visually inspect the ignition coils for signs of damage.

Were any issues found?

Yes, repair as necessary.
No, go to step 5.

Step 5. Clean the valve train and combustion chambers
Using the combustion cleaner, de-carbon the engine. After driving and clearing the combustion cleaner from the engine, erase any DTC with the scan tool. Test drive the vehicle in accordance with the when monitored conditions. With the scan tool, read DTC.

Did the DTC return?

Yes, go to step 6.
No, repair is complete.

Step 6. Check for valve train and variable valve system issues

Check the valve train for any of the following conditions, but not limited to:
  • Verify correct operation of the Camshaft phasers.
  • Verify correct operation of the Oil Control Valve.
  • Check for broken, worn or improperly installed valve springs.
  • Check for broken, worn or improperly installed camshaft followers.
  • Check for worn camshaft lobes.

Were any issues found?

Yes, Repair as necessary.
No, anything that can cause an air/fuel ratio imbalance in an individual cylinder will cause this DTC to set. Verfy all of the items in this test and other mechanical items that may cause this DTC to set. Also check for any Service Bulletins that may apply to this fault code.

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