Case IH 19680 – Engine Control Unit (ECU): Turbine upstream pressure is too low

The measured exhaust gas pressure upstream of the turbocharger turbine is lower than the possible physical minimum for the engine's current operating point. This indicates a sensor failure or drift, a circuit issue such as a short to ground or open circuit, a physical blockage in the sensor's pressure tap tube, or a severe exhaust leak prior to the turbocharger.

• Tier 4b
• Case IH Magnum
• Case IH Puma
• Case IH Maxxum
• Case N-Series Loader Backhoes (e.g., 580N)

1. 1

   Connect a diagnostic scanner and check live data for 'Turbine Upstream Pressure' with Key On, Engine Off (should closely match ambient barometric pressure).

2. 2

   Inspect the exhaust manifold, turbocharger mounting flange, and V-band clamps for soot trails indicating an exhaust leak.

3. 3

   Inspect the pressure tube connecting the sensor to the exhaust manifold for heavy soot or carbon blockages (most common mechanical cause).

4. 4

   Back-probe the sensor connector to verify a 5V reference signal and solid ground from the ECU, and check the signal wire for continuity and no short to ground.

1. 1

   Preparation

   Ensure the engine is completely cool. The exhaust manifold and turbocharger retain extreme heat and can cause severe burns.

2. 2

   Remove the Sensor and Tube

   Carefully disconnect the electrical connector from the Turbine Upstream Pressure Sensor. Use a high-quality line wrench to loosen the union nut securing the pressure tube to the exhaust manifold to prevent rounding off the fittings.

3. 3

   Clean the Pressure Tube

   If the tube is blocked with carbon, use a piece of flexible wire (like a brake cable) or compressed air to clear the blockage. If the carbon is hardened, soak the tube in a solvent/cleaner for several hours, then blow it out with compressed air until the passage is completely clear.

4. 4

   Replace Components

   If the tube was clear but the sensor failed the electrical/live data tests, install a new Turbine Upstream Pressure Sensor. If the tube is cracked or hopelessly clogged, replace the tube as well.

5. 5

   Reassembly

   Reinstall the pressure tube and sensor. Torque the fittings to the manufacturer's specifications and reconnect the wiring harness.

6. 6

   Clear Codes and Test

   Use your diagnostic scan tool to clear the 19680 fault code. Start the engine and monitor the live data to ensure the upstream pressure rises smoothly as engine RPM and turbo boost increase.