Fuel Tank Pressure Plausibility. A check engine light may be illuminated and the following fault is stored in the DME: 19401B: Fuel tank temperature-pressure sensor, plausibility; pressure to low opposed to ambient The integrated PT (pressure/temperature) sensor in the NVLD module must be calibrated at all times. If not calibrated, this fault will set when the pressure monitored has drifted out of the specified range. This condition is most common on vehicles that have had a software update with a version of ISTA/P up to 2.48.3. However, the fault may not occur immediately following programming. NOTE: If additional faults are stored for communication with the temperature sensor, further investigation is necessary. If the in-tank temperature reads a default high value such as 471°C, continue with the applicable test plan to determine the root cause. CAUSE ISTA/P versions up to 2.49.0 did not incorporate the PT sensor calibration in the update.
