P219A bank 1 air / fuel ratio imbalance
OBD2 Error Codes

P219A bank 1 air / fuel ratio imbalance

OBD-II Trouble Code - P219A - Data Sheet

P219A - Bank 1 Air/Fuel Ratio Imbalance

What does DTC P219A mean?

This is a generic Diagnostic Trouble Code (DTC) applicable to many OBD-II vehicles (1996 and newer). This may include, but is not limited to, vehicles from Toyota, Dodge, Ford, Honda, Jeep, Chevy / Chevrolet, GMC, Ram, etc. Despite the general nature, the exact repair steps may vary depending on the model year, brand, models and transmissions.

When P219A is stored, it means the powertrain control module (PCM) has detected an air-fuel ratio imbalance for the engine block that contains cylinder number one.

The PCM uses data from heated exhaust oxygen sensors (sometimes called air fuel sensors) to monitor the air-to-fuel ratio for each row of engines.

Each oxygen sensor is constructed using a zirconia sensing element located in the center of a vented steel housing. Tiny electrodes (usually platinum) attach the sensor to the wires in the oxygen sensor harness connector and the connector connects to the controller network (CAN) that connects the oxygen sensor harness to the PCM connector.

Each oxygen sensor is screwed (or twisted) into the exhaust pipe. It is positioned so that the sensing element is closer to the center of the pipe. When waste exhaust gases leave the combustion chamber (through the exhaust manifold) and pass through the exhaust system (including catalytic converters), they pass through the oxygen sensors. Exhaust gases enter the oxygen sensor through specially designed air vents in the steel housing and swirl around the sensor element. Swirling ambient air is drawn in through the wire cavities in the sensor body to fill the tiny chamber in the middle of the sensor. Then the air (in a tiny chamber) is heated. This causes the oxygen ions to produce energy, which is recognized by the PCM as voltage.

Differences between the amount of oxygen ions in the ambient air (drawn into the O2 sensor) and the number of oxygen molecules in the exhaust cause the oxygen ions inside the O2 sensor to very quickly and intermittently bounce from one platinum layer to another. ... As the pulsating oxygen ions move between the platinum layers, the output voltage of the oxygen sensor changes. The PCM sees these changes in the oxygen sensor output voltage as changes in the oxygen concentration in the exhaust gas. The voltage outputs from the oxygen sensors are lower when more oxygen is present in the exhaust (lean state) and higher when less oxygen is present in the exhaust (rich state).

If the PCM detects an air-fuel ratio imbalance for a specific engine group, code P219A will be stored and a malfunction indicator lamp (MIL) may illuminate. Most vehicles will require several ignition cycles (on failure) to turn on the warning light.

Typical oxygen sensor: P219A bank 1 air / fuel ratio imbalance

What is the severity of this DTC?

An incorrect air to fuel ratio can be the result of a lack of fuel or an excessive amount of air (vacuum). P219A should be classified as serious and should be addressed as soon as possible.

What are some of the symptoms of a P219A code?

Symptoms of a P219A trouble code may include:

  • Reduced fuel efficiency
  • Lack of overall engine performance
  • Stored Misfire Codes or Lean / Rich Exhaust Codes
  • Service engine lamp will light up soon
  • Leaks in the exhaust or intake system
  • The positive crankcase ventilation (PCV) system is leaking or the valve is stuck open.
  • Run out of fuel or low fuel pressure 
  • EVAP canister purge valve leak
  • Ignition system
  • Leaky or dirty fuel injectors
  • Exhaust Gas Recirculation (EGR)
  • Oil dipstick, tube or oil filler cap installed incorrectly

What are some of the common causes for the code?

Reasons for this code may include:

  • Engine vacuum leak (large)
  • Defective oxygen sensor / s
  • Burnt, frayed, broken, or disconnected wiring and / or connectors
  • Engine exhaust leaks
  • Defective MAF or manifold air pressure sensor.
  • Bad fuel pump or clogged fuel filter
  • Leaks in exhaust or intake system
  • The positive crankcase ventilation (PCV) system is leaking or valve stuck in the open position.
  • Run out of fuel or low fuel pressure 
  • EVAP canister purge valve leak
  • Leaky or dirty fuel injectors
  • Exhaust Gas Recirculation (EGR)
  • Oil dipstick, tube or oil filler cap installed incorrectly


To diagnose DTC P219A, a technician must:

  1. Scan codes in ECM and view the stop data frame . P219A is usually accompanied by other trouble codes that can really help with the diagnosis.
  2. Check fuel pressure, PCV system operation. 
  3. Inspect the position sensor throttle and take a look at the exhaust pipe and see if there are any traces of soot where the exhaust pipe exits.
  4. Check for leaks in the EVAP system.
  5. Perform a visual inspection of hoses, wiring and components, especially wiring oxygen sensor.
  6. If any of the above or swap tests show that one or more components are faulty, they should be replaced/repaired as needed to keep this code from returning.

What are some steps to troubleshoot the P219A?

All misfire codes, throttle position sensor codes, manifold air pressure codes, and MAF sensor codes must be reviewed before attempting to diagnose code P219A. The engine must also run smoothly and efficiently. If it is determined that a rich or lean mixture (with the engine) exists, this must be corrected as this could be the reason for the P219A being retained.

You will need a diagnostic scanner, digital volt / ohmmeter (DVOM) and reliable vehicle information source to accurately diagnose the P219A code.

You can save time by searching for Technical Service Bulletins (TSBs) that reproduce the stored code, vehicle (year, make, model, and engine) and symptoms found. This information can be found in your vehicle information source. If you find the right TSB, it can quickly fix your problem.

After you connect the scanner to the vehicle diagnostic port and get all stored codes and associated freeze frame data, write down the information (in case the code turns out to be intermittent). After that, clear the codes and test drive the car until one of two things happens; the code is restored or the PCM enters ready mode.

The code can be more difficult to diagnose if the PCM goes into ready mode at this point because the code is intermittent. The condition that led to storage of P219A may need to worsen before an accurate diagnosis can be made. If the code is restored, continue diagnostics.

You can get connector views, connector pinouts, component locations, wiring diagrams, and diagnostic block diagrams (related to the code and the vehicle in question) using your vehicle information source.

Visually inspect the associated wiring and connectors. Repair or replace cut, burnt, or damaged wiring.

If the engine runs normally and the P219A / P219B code continues to be reset, start the engine and allow it to reach normal operating temperature. Let the engine idle (in neutral or parking). With the scanner connected to the vehicle diagnostic port, observe the oxygen sensor input in the data stream. Narrow down your data stream to include only relevant data for a faster response.

If the oxygen sensors are operating normally, the voltage across the oxygen sensors upstream of the catalytic converter will cycle continuously from 1 to 900 millivolts when the PCM enters closed loop mode. The post-cat sensors will also cycle between 1 and 900 millivolts, but they will be set at a certain point and remain relatively stable (compared to pre-cat sensors). Oxygen sensors that are not working properly should be considered defective if the engine is in good working order.

  • In most cases, you will fix this code by fixing a rich or lean engine.

Common Mistakes

The following are some of the most common mistakes a technician can make when diagnosing a P219A code:

  • No freeze frame data check to determine the conditions under which the DTC was set.
  • Do not check documents vehicle to make sure the code is correct and not other code.
  • Use of diagnostic equipment that misinterprets DTCs and reports scan results to them.
  • Not all tests or paging tests required to identify faulty components are not run. It may be easy to identify one or two faulty components, but all tests must be performed in order to make an accurate diagnosis.
  • Before replacing any components or parts, always check their compatibility with the vehicle.

Related codes

  • P219A is associated with and may be accompanied by the following codes:
  • P0491 - Incorrect purge flow of the fuel vapor emission control system
  • P0505 - Injector circuit / open circuit - cylinder 5
  • P1294 - Fuel level signal circuit malfunction
What is P219A Engine Code [Quick Guide]

Need more help with the P219A code?

If you still need help regarding DTC P219A, post a question in the comments below this article.

NOTE. This information is provided for informational purposes only. It is not intended to be used as a repair recommendation and we are not responsible for any action you take on any vehicle. All information on this site is protected by copyright.

3 comment

  • José

    My classic 12/13 is giving error P219a. Nobody finds the defect. I've already changed the spark plug, I've changed the first probe and nothing.

  • Thomas Medeiros

    Drill a hole in the catalytic converter, as it must be clogged.


    my classic 2013/14 is generating the p219a code. I already changed the map sensor lambda probe pre and also changed the catalytic converter and this code does not disappear

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