Case IH 295 – ENG (Engine Control Module / ECM): Ambient Air Pressure data invalid

This code is triggered when the ambient air (barometric) pressure sensor reads an erratic value at initial key-on. The Engine Control Module (ECM) compares the barometric pressure reading to other engine pressure sensors before the engine is cranked. If the barometric pressure value does not match the other sensors within a pre-defined tolerance, or if the sensor is stuck in-range, the ECM logs fault code 295. This condition typically results in an engine power derate.

• MX Magnum
• STX Steiger
• Magnum Series Tractors
• Magnum 265
• Magnum 280
• Magnum 295
• Magnum 310
• Magnum 335
• Steiger Series Tractors
• Puma Series Tractors
• Farmall Series Tractors

1. 1

   Perform a Key-On, Engine-Off (KOEO) test by turning the keyswitch ON and waiting 15 seconds before cranking to allow the ECM diagnostic to run.

2. 2

   Verify sensor values using an electronic service tool in the KOEO state (barometric pressure should match local atmospheric pressure, and intake manifold pressure should read exactly 0.0 in-hg).

3. 3

   Inspect the sensor signal and return lines for high resistance, corrosion, or a short circuit.

4. 4

   Verify that the correct pressure/temperature sensor is installed in the correct location, as swapping the manifold pressure sensor with the ambient pressure sensor is a known root cause.

1. 1

   Locate the Sensor

   The ambient air/barometric pressure sensor is typically mounted on the main branch of the engine wiring harness near the Engine Control Module (ECM).

2. 2

   Inspect the Harness

   Disconnect the sensor and inspect the 3-pin connector for moisture, pushed-back pins, or wire chafing. Repair the pigtail harness if high resistance is found.

3. 3

   Replace the Sensor

   If the wiring is intact but the sensor failed the KOEO pressure comparison test (or is stuck in-range), remove the faulty sensor and install a new OEM replacement.

4. 4

   Clear the Fault Code

   Manual clear: The ECM will turn off the Malfunction Indicator Lamp (MIL) after 3 consecutive ignition cycles where the diagnostic runs (key on for 15 seconds) and does not fail. The code will clear from inactive memory after 40 consecutive drive cycles. Tool clear: Use a diagnostic service tool to manually clear the permanent fault code from the ECM.