Code Definition

P1DDE — Ignition Run/Start Input 1/2 Correlation

System: Powertrain  |  Type: Manufacturer-Specific  |  Make: Jeep

About P1DDE

P1DDE is a manufacturer-specific powertrain diagnostic trouble code recorded for Jeep vehicles. It belongs to the P-prefix family of codes, which covers engine, transmission, emissions, or fuel-system faults.

When P1DDE is stored, the module has detected a correlation fault — two sensors that should track each other have diverged beyond tolerance.

Scanning & clearing: A generic OBD-II scan tool will usually read and clear powertrain (P) codes. For live data, freeze-frame capture, and bi-directional tests you may need a more capable scan tool that supports the vehicle's ECM protocol.

P1DDE is a manufacturer-specific code. The same code string on a different make may have a different meaning. Always confirm the code's definition against the vehicle's service information for the specific make and model under test.

Code Information

The Powertrain Control Module (PCM) receives more than one ignition run and start input, typically from the ignition switch and the Body Control Module, and compares them as a redundant check on the true ignition state. DTC P1DDE is set when the PCM detects that ignition input 1 and input 2 do not agree or do not transition together in the expected relationship within a calibrated time window. This is a correlation or plausibility fault between the two ignition state signals rather than a single open or short. Depending on which signal is wrong, the engine may crank or run poorly, stall, fail ...

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