Diagnostic Trouble Code P219A Definition, Possible Causes, & Diagnosis

Diagnostic Trouble Code P219A Definition

The diagnostic trouble code (DTC) P219A indicates an ongoing air/fuel imbalance between the bank 1 cylinders. The engine control module (ECM) monitors feedback from the air/fuel ratio sensor while the engine is running and in combination with information from the crankshaft position sensor is able to detect the average air fuel ratio of each cylinder in the exhaust stream. If the ECM detects that one or more bank 1 cylinders is consistently rich or lean compared to the others, it will set P219A and illuminate the check engine light.

P219A Possible Causes

Before determining possible causes of P219A, we need to review some additional information and confirm that P219A is the priority DTC. First, we need to check for any additional engine DTC's related to a rich or lean condition, engine misfires, and air/fuel ratio sensor performance. Any such DTC's will typically be prioritized over P219A and should be diagnosed first. The air/fuel ratio sensor is not typically a top possible cause of P219A as the DTC sets due to abnormal readings only at certain crankshaft positions.

Next, we want to review freeze frame data to see the short term fuel trim at the time the DTC set and check for a lean or rich condition on one or both banks. A lean condition often points to an intake manifold leak, exhaust manifold leak, or fuel injector issue in the case of P219A while a rich condition in the context of P219A could be due to an intake or exhaust restriction, or a fuel injector issues. P219A with no overall rich or lean condition may point to a mechanical compression imbalance between cylinders.

Here are some common possible causes of P219A to consider:

• Fuel injectors

• Spark plugs

• Engine mechanical (compression imbalance between bank 1 cylinders)

• Intake manifold leak

• Exhaust manifold leak

• Intake or exhaust restriction

• Exhaust leak near the air/fuel ratio sensor

P219A Diagnosis

Here are some general steps to eliminate possible causes and aid in the diagnosis of P219A:

Test the intake and exhaust systems for leakage: Particularly at the intake and exhaust manifolds, near the air/fuel ratio sensor, and anywhere else that the leak may affect only certain cylinders.

Inspect the condition of the spark plugs: Worn, damaged, or incorrect spark plugs can cause incomplete combustion and potentially lead to P219A.

Inspect the bank 1 catalytic converter: If a rich condition is present, this can be caused by a restriction in the catalytic converter. Inspection can be done by removing the air/fuel ratio and oxygen sensors and using a borescope to inspect the catalyst for deterioration or damage.

Inspect the intake system for a restriction: Dirty air filters, damaged intake components, or debris in the system can create a restriction and potentially cause P219A.

Perform a compression test: Focus on the variance in readings between the bank 1 cylinders. Service information will typically provide a compression variance spec between cylinders that should not be exceeded.

Test the response and range of the air/fuel ratio sensor: Use a suitable scan tool to command the fuel trim up and down. Confirm that the air/fuel ratio sensor reading responds as expected and through its full voltage output range.

Replace the fuel injectors: If all other possible causes have been eliminated, it is most likely that the fuel injectors are causing the imbalance.