D Group 28 Troubleshooting MID 128 PPID 270 NOx Sensor MID 233 Fault code sent by MID 128 Engine control unit. 35 Type of fault FMI Description: Fault Condition: Possible Symptoms:
Possible Cause FMI 2 • Data erratic, intermittent or incorrect • Removed • Plausibility • Malfunction indicator lamp illuminated • NOx sensor removed (measures surround air) • Exhaust system leakage • Air intake leakage • Faulty NOx sensor FMI 3 • Voltage above normal or shorted to high source • Short Circuit, NOx signal • N/A • Faulty cabling between NOx sensor and NOx sensor ECU • Faulty NOx sensor FMI 5 • Current below normal or open circuit • Open Circuit, NOx signal • N/A • Faulty cabling between NOx sensor and NOx sensor ECU • Faulty NOx sensor FMI 9 • Abnormal update rate (missing sensor signal • Abnormal update • N/A • Missing signal from NOx sensor FMI 10 • Abnormal rate of change • Stuck • N/A • Exhaust system leakage • Air intake leakage • Faulty NOx sensor FMI 12 • Bad Intelligent Device or Component • Incorrect value • N/A • Faulty NOx sensor FMI 13 • Out of calibration • Range check • N/A • Faulty NOx sensor FMI 14 • Special instructions • Missing signal from sensor due to battery voltage • N/A • Voltage to NOx sensor is too high