P2228 – Barometric Pressure Circuit Low

System: Powertrain | Standard: ISO/SAE Controlled | Fault type: Circuit Low

Definition source: SAE J2012/J2012DA (industry standard)

DTC P2228 indicates the powertrain control module has detected a low electrical signal condition in the barometric pressure circuit. Because sensors, wiring routes, and diagnostic thresholds vary by vehicle, the exact conditions that trigger this code can differ; always confirm the circuit layout, reference voltage strategy, and pinouts in the correct service information before testing. A “circuit low” fault typically points to a short-to-ground, excessive resistance on the signal line, a missing/low reference voltage, or a sensor that is pulling the signal down. Addressing wiring integrity first prevents unnecessary parts replacement.

What Does P2228 Mean?

P2228 – Barometric Pressure Circuit Low means the control module has determined the barometric pressure (BARO) sensor circuit voltage is below the expected calibrated range for a defined period of time. Per SAE J2012 conventions, the DTC format identifies this as a standardized powertrain diagnostic code, while the text description defines the specific fault: a low signal condition in the BARO circuit. The BARO signal is used to estimate ambient air pressure for engine load calculations and related strategies; when the circuit reads low, the module may substitute a default value and set a fault.

Quick Reference

  • System: Powertrain
  • Official meaning: Use the official definition provided by the data source for this code.
  • Standard: ISO/SAE Controlled
  • Fault type: Circuit Low
  • Risk level: Moderate; drivability and fuel/air calculations may be affected, but severity varies by vehicle and operating conditions.

Symptoms

  • Check engine light illuminated (MIL on)
  • Reduced power or limited engine performance under load
  • Rough running or hesitation during acceleration
  • Hard starting or extended crank in some conditions
  • Poor fuel economy due to substituted/default pressure values
  • Black smoke or rich/lean driveability complaints depending on strategy
  • Secondary codes may appear that relate to air metering or sensor reference voltage circuits

Common Causes

  • Signal circuit short-to-ground between the barometric pressure (BARO) sensor and the engine control module (wiring insulation damage, pinched harness)
  • Low 5-volt reference supply to the BARO sensor (short-to-ground on the reference circuit or excessive load on the shared reference circuit)
  • High resistance or open power feed to the sensor where applicable (sensor not receiving proper supply, causing a low output)
  • Sensor ground circuit fault (poor ground path, corrosion, loose terminal) pulling sensor output low
  • Connector issues at the sensor or control module (water intrusion, corrosion, spread terminals, poor pin fit) creating a low-voltage signal
  • BARO sensor internal failure producing a consistently low output voltage
  • Harness routing problems causing intermittent contact with ground (chafing on brackets, engine components, or body seams)
  • Control module input circuit problem (less common): skewed low bias on the BARO signal input

Diagnosis Steps

Tools that help include a scan tool with live data and freeze-frame access, a digital multimeter (with back-probing leads), and basic hand tools for connector inspection. A wiring diagram and connector pinout for the specific vehicle are essential because BARO sensor location and circuit design vary by vehicle. If available, a breakout lead set and contact-cleaning supplies can improve test accuracy and prevent terminal damage.

  1. Confirm the stored code and capture freeze-frame data. Note engine load, RPM, ignition state, and any related sensor or 5-volt reference codes. Clear codes and see if P2228 returns immediately or after a drive cycle.
  2. Check scan tool live data for barometric pressure reading and the BARO sensor signal voltage (if the PID is available). Look for a value that is fixed unusually low or drops out intermittently, consistent with a circuit-low fault.
  3. Perform a visual inspection of the BARO sensor, its connector, and harness routing. Look for rubbed-through insulation, pinched wiring, oil/water intrusion, and evidence of prior repairs. Correct obvious harness damage before deeper testing.
  4. With key on and engine off (as applicable), unplug the BARO sensor connector and inspect terminals closely. Check for corrosion, bent pins, spread terminals, and poor terminal tension. Repair/replace terminals as needed and ensure the connector locks fully.
  5. Verify the 5-volt reference at the sensor connector (if equipped). Using a multimeter, measure between the reference pin and sensor ground pin. If the reference is low or missing, isolate whether the reference is being pulled down by another component on the same reference circuit (varies by vehicle) by disconnecting other sensors one at a time per service information.
  6. Verify sensor ground integrity. Measure voltage drop from the sensor ground pin to battery negative with the circuit powered (key on). A measurable voltage drop indicates excessive resistance in the ground path; repair the ground circuit, splice, or ground point as required.
  7. Check the signal circuit for short-to-ground. With the sensor unplugged and the control module connector accessible as specified by service information, test resistance between the signal wire and chassis ground. Near-zero resistance suggests a short-to-ground; locate the chafe point and repair the harness.
  8. Check signal circuit continuity and resistance end-to-end (sensor connector to control module pin). High resistance, intermittent continuity, or open readings indicate a wiring/terminal fault that can force the control module to see a low signal; repair the wire, terminal, or connector as needed.
  9. Perform a wiggle test while monitoring the BARO PID and/or signal voltage. Manipulate the harness near known rub points and connectors. If the reading drops low during movement, focus on that section for terminal tension issues or hidden conductor damage.
  10. If reference, ground, and wiring tests pass, evaluate the BARO sensor itself using the service procedure (some designs allow a signal sweep check). If the sensor output remains low with good reference and ground, replace the sensor.
  11. If all external circuits and the sensor test good, follow service information for control module input testing. A confirmed low-biased input after all wiring checks may indicate a control module fault or pin-fit issue at the module connector (less common).

Professional tip: When chasing a circuit-low fault, prioritize tests that can prove a short-to-ground or a pulled-down 5-volt reference. A quick way to narrow the search is to verify whether the 5-volt reference returns to normal when the suspected sensor is unplugged; if it does, the sensor or its connector/wiring near the sensor is a prime suspect. Always back-probe carefully and avoid forcing probes into terminals, which can create new intermittent low-signal problems.

Possible Fixes

  • Repair wiring faults that can pull the BARO signal low, such as a short-to-ground, chafed insulation, pinched harness sections, or moisture-wicking in the loom; restore proper routing and protection afterward.
  • Clean, dry, and reseat the BARO sensor (or related pressure sensor) electrical connector; repair or replace damaged terminals, locks, or seals that may be creating an unintended ground path or high resistance on the reference supply.
  • Verify and restore the sensor’s reference voltage and ground integrity; repair open power/5V reference feed issues or poor grounds that can cause the circuit to read low under load.
  • Replace the barometric pressure sensor only after confirming the circuit, reference supply, and ground are correct and the signal remains low with a known-good electrical path.
  • If the BARO function is integrated into another sensor (varies by vehicle), repair or replace the applicable sensor assembly after circuit checks confirm the low condition originates internally.
  • After repairs, clear the DTC and perform a confirmatory road test or key-cycle test while monitoring the BARO parameter to verify the signal no longer drops low and the code does not reset.

Can I Still Drive With P2228?

Driving with P2228 is sometimes possible, but it depends on how the powertrain controller uses the barometric pressure input for fueling and load calculations. If you notice reduced power, poor acceleration, unstable idle, or stalling, avoid driving and address the fault promptly because an incorrect low BARO signal can lead to improper air-fuel and timing decisions. If the vehicle enters a reduced-power mode or shows severe drivability symptoms, it is safer to stop and repair the electrical issue before continued operation.

What Happens If You Ignore P2228?

Ignoring P2228 can result in ongoing drivability problems such as hesitation, poor throttle response, rough running, or reduced fuel economy due to incorrect air-density calculations. The controller may rely on default values, which may not match actual conditions, and the vehicle may repeatedly enter a limited-performance strategy. A persistent circuit-low condition can also mask additional faults in the same reference/ground circuits, making future diagnostics harder and potentially leading to intermittent stalling or difficulty starting if the electrical problem worsens.

Related Codes

  • P2268 – Water in Fuel Sensor Circuit Intermittent
  • P2267 – Water in Fuel Sensor Circuit High
  • P2266 – Water in Fuel Sensor Circuit Low
  • P2265 – Water in Fuel Sensor Circuit Range/Performance
  • P2264 – Water in Fuel Sensor Circuit
  • P2230 – Barometric Pressure Circuit Intermittent
  • P2229 – Barometric Pressure Circuit High
  • P2227 – Barometric Pressure Circuit Range/Performance
  • P2226 – Barometric Pressure Circuit
  • P2299 – Brake Pedal Position / Accelerator Pedal Position Incompatible

Key Takeaways

  • P2228 indicates a barometric pressure circuit low condition, which points to an electrical signal that is lower than expected.
  • Prioritize checks for short-to-ground, connector moisture/corrosion, and reference voltage or power feed issues that can force the signal low.
  • Replace the sensor only after verifying wiring, terminals, reference supply, and ground are correct and stable.
  • A confirmatory drive or logging test after repair is important to ensure the BARO parameter stays plausible and the DTC does not return.
  • Continued driving is not recommended if the vehicle shows stalling, reduced power, or unstable idle.

FAQ

Is P2228 usually caused by the sensor or the wiring?

P2228 is often caused by wiring, connector, or power/ground problems that pull the barometric pressure signal low, such as a short-to-ground or a missing/weak reference supply. The sensor can fail, but it should be replaced only after circuit checks confirm the electrical feed and ground are correct and the signal still remains low.

What electrical issue most commonly creates a “circuit low” reading?

A “circuit low” condition is most commonly created by a signal wire shorted to ground, moisture or corrosion bridging terminals, or an open in the reference power feed that prevents the sensor from producing a normal voltage output. Poor ground integrity can also skew the signal low depending on circuit design.

Will clearing the code fix P2228?

Clearing the code only resets stored fault information; it will not fix the underlying circuit-low condition. If the short-to-ground, reference voltage problem, or connector fault is still present, P2228 will typically return after the monitor runs again, sometimes immediately during the next key cycle.