Power Solutions International, Inc.

DTC 121

UnclassifiedGeneral

What This Code Means

MIL ON (Malfunction Indicator Lamp ON); Engine shutdown

Possible Causes

  • •Faulty ECM
  • •Faulty ECM connection
  • •Intermittent Problem
  • •Problem with the TPS signal circuit
  • •TPS 1 percentage is 20% or more lower than TPS 2 percentage
  • •TPS1 or TPS2 signal shorted to ground in harness
  • •Throttle is out of specification

Suggested Actions

  1. 1Connect TPS1 signal to the 5V reference at throttle connector while observing TPS 1 voltage, repeat for TPS2, and check if DST displays both TPS1 and TPS2 voltage over 4.90 VDC.
  2. 2Key ON, Engine Off, System Mode set to 'Stopped', Enable 'DBW Test' mode, slowly depress FPP sensor to check for TPS1 and TPS 2 calibration differences.
  3. 3Key Off, disconnect throttle from harness, set Key ON, Engine Off, System Mode to 'Stopped', Enable 'DBW Test' mode, and check if the voltage for both TPS1 and TPS2 is <0.100 VDC.
  4. 4Key Off, disconnect wire harness header from ECM, carefully remove yellow lock from header at device output terminal, and check resistance between MAP input at ECM header and signal at device (ensuring resistance is <5 ohms).
  5. 5Perform the On-Board (OBD) System Check.

Related Power Solutions International, Inc. Fault Codes

DTC 123DTC 127DTC 108DTC 129DTC 89 20DTC 148DTC 15 74DTC 234DTC 2 34DTC 238DTC - 520DTC 299
Browse all Power Solutions International, Inc. fault codes

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