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DTC codes / P22xx · Fuel and air metering (injector circuits) / P2228

P2228Barometric Pressure Circuit Low

P2228 means the engine control module (ECM) has detected a barometric pressure (BARO) sensor signal voltage that is lower than the expected range for current operating conditions. The barometric pressure sensor measures atmospheric pressure, and the ECM uses that reading to calculate air density and adjust fuel delivery; a low signal tells the ECM the vehicle is at a higher altitude than it really is.

SystemPowertrain
Code typeGeneric (all makes)
SeverityMedium
Fix difficultyIntermediate
AreaFuel and air metering (injector circuits)

Symptoms you may notice

  • Illumination of the check engine light, often with no other noticeable symptoms
  • Rough idle or unstable engine operation as the ECM miscalculates fuel mixture
  • Reduced fuel economy because the ECM commands a richer or leaner mixture than needed
  • Hesitation or stumble during acceleration, especially at higher altitudes
  • In rare cases, a no-start condition if the BARO signal is completely lost and the ECM cannot default to a safe value

Common causes, most likely first

  1. Faulty barometric pressure sensor internally shorted or failing to produce the correct voltage
  2. Damaged or corroded wiring between the BARO sensor and the ECM, including a short to ground on the signal circuit
  3. Poor electrical connection at the sensor or ECM connector, such as loose pins or water intrusion
  4. Contaminated or blocked sensor port, preventing atmospheric pressure from reaching the sensing element
  5. Failed ECM driver circuit for the BARO sensor reference or signal return
  6. Aftermarket air intake or filter modifications that disturb the sensor's exposure to ambient pressure

How to diagnose and fix it

  1. Connect a scan tool and record the BARO sensor voltage and the BARO reading in kPa or inHg, then compare it to a known-good value for your altitude
  2. Visually inspect the sensor, its connector, and the wiring harness for damage, corrosion, or loose pins, and repair as needed
  3. Check the sensor's reference voltage and ground circuits with a digital multimeter to confirm the ECM is supplying the correct power and ground
  4. Backprobe the signal wire at the sensor and at the ECM to check for a short to ground or an open circuit, and repair the harness if a fault is found
  5. Remove and inspect the sensor for contamination or a blocked pressure port, and clean or replace it if necessary
  6. If wiring and connections are good, substitute a known-good BARO sensor and clear the code to see if it returns
  7. After repairs, clear the diagnostic trouble codes (DTCs), perform a road test, and verify that the BARO reading matches actual atmospheric pressure and that P2228 does not reset

Barometric sensor faults that fool technicians

  • A low BARO signal can be caused by a short to ground in the signal wire, which is often overlooked when the sensor itself tests good on the bench.
  • Some vehicles use the mass air flow (MAF) sensor's built-in barometric pressure reading, so a P2228 may actually point to a failing MAF sensor rather than a separate BARO sensor.
  • The ECM may substitute a default barometric pressure value when the sensor fails, allowing the engine to run almost normally and masking the fault until the check engine light appears.
  • Altitude changes during driving can trigger a P2228 if the sensor is slow to respond or if its reference voltage is marginal, so testing at different elevations can reveal an intermittent fault.
  • A dirty or clogged air filter or a restricted intake can create a low-pressure condition that the BARO sensor interprets as a low signal, leading to a misdiagnosis of the sensor itself.

Can I keep driving with P2228?

You can usually drive with P2228 because the ECM substitutes a default barometric pressure value, but fuel economy and performance may suffer and the engine may run poorly at high altitude. Avoid sustained heavy loads or towing until the fault is repaired, and have the vehicle scanned promptly if the check engine light is flashing or drivability worsens.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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