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DTC codes / Toyota codes / P1100

P1100 · ToyotaBARO Sensor Circuit

P1100 on Toyota vehicles indicates that the engine control module has detected an abnormal signal from the barometric pressure sensor circuit, which measures atmospheric pressure for altitude compensation. The computer compares the BARO sensor voltage against expected values and sets this code when the signal falls outside the normal operating range or is inconsistent with other pressure sensors.

SystemPowertrain
Code typeToyota specific
SeverityLow
Fix difficultyIntermediate
AreaFuel and air metering

Symptoms you may notice

  • Illumination of the check engine light, often with no other noticeable symptoms
  • Rough idle or poor engine performance at high altitudes
  • Decreased fuel economy due to incorrect air-fuel mixture calculation
  • Hesitation or stumble during acceleration
  • In rare cases, a no-start condition or stalling when the BARO signal is completely lost

Common causes, most likely first

  1. Faulty barometric pressure sensor (BARO sensor) internal failure
  2. Damaged or corroded wiring harness or connector at the BARO sensor
  3. Open or short circuit in the BARO sensor signal circuit
  4. Poor electrical connection at the engine control module (ECM) connector
  5. Failed ECM driver circuit for the BARO sensor
  6. Contamination or blockage of the sensor sensing port
  7. Aftermarket air intake or modifications that affect sensor readings

How to diagnose and fix it

  1. Connect a scan tool and record the BARO sensor voltage and pressure readings with key on, engine off, comparing them to actual atmospheric pressure for your altitude
  2. Visually inspect the BARO sensor connector and wiring for corrosion, loose pins, or physical damage
  3. Check the sensor reference voltage and ground circuits with a multimeter to confirm power and ground are present
  4. Perform a wiggle test on the harness while watching live data to detect intermittent connection issues
  5. Replace the BARO sensor if voltage readings are implausible or the sensor fails a known-good comparison test
  6. Clear the code and test-drive the vehicle to verify the repair and ensure the code does not return
  7. If the code persists after sensor replacement, diagnose the ECM signal circuit and ECM itself for internal faults

BARO sensor faults that mimic other issues

  • A failing BARO sensor often produces no drivability symptoms at sea level because the ECM can substitute a default value, so the code may be the only clue.
  • Technicians frequently misdiagnose P1100 as a mass airflow sensor problem because both affect fuel trim, but the BARO sensor reads atmospheric pressure only with the key on and engine off.
  • Corroded pins at the ECM connector are a common hidden cause that a simple sensor swap will not fix, so always inspect the ECM side of the circuit.
  • Aftermarket performance air filters or intake piping can disturb the BARO sensor's reference chamber on some Toyota models, causing false readings.
  • The BARO sensor is sometimes integrated into the mass airflow sensor housing on certain Toyota engines, so replacing the MAF may be necessary even though the code points to BARO.

Can I keep driving with P1100?

The vehicle is generally safe to drive with P1100 because the ECM substitutes a default barometric pressure value, but you may notice reduced performance or fuel economy at high altitudes. Avoid towing heavy loads or driving in mountainous terrain until the fault is repaired, as the engine may not compensate properly for altitude changes.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

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

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