P2227
Pressure Sensor A Circuit Range/PerformanceP2227 is a generic OBD-II powertrain diagnostic trouble code: Pressure Sensor A Circuit Range/Performance. It is logged by the engine control unit when the scr/adblue monitor detects that a specific fault threshold has been exceeded — typically resulting in the malfunction-indicator lamp (MIL / check-engine light) being illuminated.
What P2227 means
P2227 — Barometric Pressure Sensor 'A' Circuit Range/Performance — is triggered when the ECM/PCM determines that the BARO sensor's output does not match the expected value for the current operating conditions. The barometric pressure sensor measures ambient atmospheric pressure so the ECM can compensate fuel delivery, ignition timing, and boost targets for altitude. At key-on and at wide-open throttle the ECM uses BARO as an independent cross-check against the manifold absolute pressure (MAP) reading; if the two diverge beyond calibrated limits, or if BARO reads outside the plausible voltage window (nominally 0.5–4.5 V on a 5 V reference), P2227 is set.
Unlike a full circuit failure code (which indicates an open or shorted wire), a Range/Performance code means the signal is electrically present but logically implausible. This is frequently caused by high-resistance connections — corroded connector pins or a partial break in the sensor ground — that attenuate the return voltage without eliminating it entirely. A wiring fault is statistically more common than sensor failure itself.
On many modern vehicles the BARO sensor is integrated inside the MAP sensor or the PCM itself. Replacing the wrong component wastes money; always verify signal voltage and the 5 V reference and ground circuits at the sensor connector before condemning any hardware. Altitude and weather-related pressure swings are expected and should not trigger this code on a healthy system.
Common causes
Most-frequently reported root causes when P2227 is logged.
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1
High-resistance or corroded connector pins on the BARO or MAP sensor circuit attenuating the return signal.
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2
Open or intermittent break in the sensor ground wire causing offset voltage readings.
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3
Short to ground on the signal wire pulling the return voltage below the expected range.
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4
Short to power on the signal wire pushing the return voltage above 4.5 V.
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5
Failed BARO sensor with drifted internal circuitry producing an out-of-range voltage.
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6
BARO sensor integrated inside the MAP sensor — MAP sensor failure presents as P2227 on these vehicles.
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7
PCM input driver fault or software error misinterpreting a valid sensor voltage.
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8
Water intrusion into the sensor connector creating a conductive bridge between pins.
Symptoms drivers notice
How to diagnose P2227
A typical diagnostic flow when this code is present.
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1
Retrieve freeze-frame data and note the BARO voltage; compare it to the expected value for local altitude (sea-level standard is approximately 101.3 kPa / ~4.0 V).
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2
With key on, engine off, monitor live BARO sensor voltage on a scan tool and verify it falls within 0.5–4.5 V; wiggle the harness near the connector and watch for signal dropout.
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3
Inspect the BARO/MAP sensor connector for corroded or bent pins, moisture, and broken wires; clean with electrical contact cleaner and retest.
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4
Back-probe the sensor connector and verify the 5 V reference and a clean ground (< 0.1 V drop to chassis ground) before suspecting the sensor itself.
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5
If the vehicle uses a combined MAP/BARO sensor, cross-check MAP voltage at idle; an implausible MAP reading alongside P2227 suggests sensor replacement is warranted.
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6
Clear the code after any repair and perform a road test with a data log to confirm BARO remains stable across throttle positions and RPM.
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7
If all wiring and sensor checks pass, inspect PCM connector integrity; an internal PCM fault is a last resort diagnosis.
Related powertrain codes
- B0001 — PCM Discrete Input Speed Signal Error
- B0004 — PCM Discrete Input Speed Signal Not Present
- C0359 — Four Wheel Drive Low Range (4LO) Discrete Output Circuit
- C0362 — 4LO Discrete Output Circuit High
- P2000 — NOx Adsorber Efficiency Below Threshold Bank 1
- P2001 — NOx Adsorber Efficiency Below Threshold Bank 2
Frequently asked questions
Can driving at high altitude cause P2227 to set falsely?
No. The sensor is designed to read across the full range of atmospheric pressures encountered at any legal driving altitude. A genuine P2227 means the signal is outside the sensor's designed operating window or is inconsistent with the MAP reading — not simply that ambient pressure is lower than sea level.
Is the BARO sensor always a separate part?
Not always. On many engines (e.g. various GM, Ford, and Chrysler applications) the BARO function is built into the MAP sensor or even into the PCM itself. On these vehicles, P2227 may point to the MAP sensor or the PCM rather than a standalone barometric pressure sensor.
Why does the ECM cross-check BARO against MAP?
At key-on before cranking and at wide-open throttle (where manifold pressure approaches atmospheric), MAP should equal BARO. If the two readings diverge beyond the manufacturer's calibrated tolerance, the ECM flags one of them as implausible. This rationality check catches slow sensor drift that would otherwise go undetected.
Does P2227 affect turbo boost control?
Yes, on turbocharged engines. The ECM uses BARO to calculate a boost pressure target relative to atmospheric pressure. An incorrect BARO reading can cause the ECM to command too much or too little boost, affecting performance and potentially triggering additional turbo-related fault codes.
Disabling P2227 in software
RaceTune can permanently disable P2227 — and any other OBD-II diagnostic trouble code — on every ECU family we support. The monitor is disabled inside the ECU itself, so the fault stops being logged: the warning light stays off and the engine never enters limp mode for this code. The change is tied to your exact software version.
Software modifications affect emissions compliance and are not road-legal in many jurisdictions. RaceTune service files are intended for motorsport, off-road, and export use.
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