P1693 — DTC Detected in Companion Module — 5.9 Cummins 24-Valve (VP44)
P1693 is a companion/secondary code on the 5.9L Cummins 24-valve VP44 platform. It indicates the PCM has stored another fault in a separate module and is…
What it means
P1693 means the PCM detected a fault code in another controller and is mirroring it. On this platform the code is a flag, not a primary engine fault. Retrieve companion codes from the PCM and the companion module (typically the transmission controller) to identify the actual failure.1
Most likely causes
- Companion fault stored in another module (e.g., transmission controller) – the actual DTC is in the companion module — P1693 is a flag that another module has set a fault. The root cause is the companion DTC, not the engine itself. Read codes from all modules and address the companion code first.1
- PCM communication / data-link issue preventing companion code retrieval — Intermittent CAN/PCI bus or power/ground issues can cause the PCM to set P1693 when it cannot read the companion module. Verify module communication, powers, grounds, and data-link integrity before assuming a hard fault.1
- Recent module replacement or reflash with mismatched calibration — After module service, a mismatch or incomplete flash can cause the PCM to mirror a spurious companion fault. Confirm module part numbers and calibrations match the 1998.5–2002 5.9L VP44 configuration.1
How to diagnose
- Verify platform applicability: 5.9L Cummins 24-valve VP44 1998.5–2002 with Bosch VP44 rotary pump, fixed-geometry HX35/HY35 turbo, APPS pedal, grid heater, no EGR/DPF/SCR/common rail.
- Use a scan tool to read all modules. Record the companion DTC(s) referenced by P1693; P1693 alone is not diagnostic.
- If no companion code is present, check PCM powers, grounds, and data-link connections for corrosion/loose terminals.
- Clear codes, cycle ignition, and re-scan to confirm P1693 returns with or without a companion fault.
Parts and tools you may need
- OBD-II scan tool capable of reading PCM and transmission controller codes
- Digital multimeter
- Wiring diagram for 1998.5–2002 Ram 2500/3500 chassis
Tools you’ll need
- OBD-II scan tool with module coverage — Reads PCM and companion modules to retrieve the mirrored DTC that P1693 references.
- digital multimeter — Checks PCM powers, grounds, and data-link voltages for communication issues preventing companion code retrieval.
- wiring diagram / service manual — Identifies correct data-link pins and module locations for the 5.9 Cummins VP44 platform.
Rough cost and difficulty
| Likely repair | Parts | Shop labor | Who usually does it |
|---|---|---|---|
| ECM/PCM software update | — | 0.5–1.5 hrs | Shop |
| Shop diagnosis | — | 1–2 hrs | Shop |
| Wiring or connector repair | $10–$100 | 1–4 hrs | DIY with tools and a manual |
Typical US independent-shop figures; labor runs about $120–$180 per hour (dealers charge more). Confirm the diagnosis before buying parts.
When to see a pro
If companion codes indicate internal transmission faults, high-pressure fuel system work, or require module programming, have a qualified diesel technician perform diagnosis and repairs. Do not attempt safety-critical or high-pressure fuel repairs without proper training and equipment.
Check for recalls
Recalls are tied to your truck’s VIN, so check yours directly: enter the VIN at NHTSA’s recall lookup. Open safety recalls are repaired free at a dealer.
Sources
Repair videos: P1693 on the 5.9 Cummins 24V
Third-party videos, not ours — picked for this engine. Confirm anything against the factory service information for your truck.
Spotted an error, or something missing? Tell us
Run a 5.9 Cummins 24-Valve (VP44)? This goes straight to the editor — it is not published.