Engine Torque Output Message
This code indicates an issue with the engine torque output message from the ECU to the transmission control module.
Heads up: this code wasn't in our hand-written library yet, so DiagCoach AI built this page on the fly. Double-check critical specs against service info before condemning parts.
What it means (plain English)
The engine's computer is not sending the correct information about how much power the engine is producing to the transmission, which can affect shifting and performance.
What the computer is actually seeing
The Engine Control Unit (ECU) monitors engine performance and calculates torque output. If the signal sent to the Transmission Control Module (TCM) is irregular or missing, this fault code activates.
What a healthy reading looks like
Torque output typically ranges from 0 to 2000 Nm, depending on engine load and RPM.
Guided diagnostic — the DiagCoach way
Don't just throw parts at it. Walk through these in order — each step tells you whether to keep going or stop and fix what you found.
- 11. Check for any visible wiring damage or loose connectors between the ECM and TCM. If found, repair or replace as necessary. => Decision: If fixed, clear the code and retest.
- 22. Verify the battery voltage; it should be between 12.4V to 14.8V while running. Low voltage can cause communication issues. If voltage is low, charge or replace the battery. => Decision: If battery is good, move to Step 3.
- 33. Scan for additional fault codes. If other related codes are present, troubleshoot those first as they may point to the root cause. => Decision: If SPN 178 is the only code, move to Step 4.
- 44. Use a data logger to monitor real-time torque output from the engine. Check if the values are within expected limits during different load conditions. => Decision: If values are erratic, suspect a faulty ECM; if values are normal, suspect a TCM issue.
Common causes
- Faulty engine control module (ECM)
- Bad wiring or connectors between ECM and TCM
- Faulty transmission control module (TCM)
- Incorrect engine load parameters
Typical repair cost
$$$
Related codes
Frequently asked questions
Is it safe to drive with this code active?
It is not recommended to drive as shifting may be affected, leading to drivability issues.
Will this code come back?
If the underlying issue isn't fixed, yes, it will likely return after clearing.
What happens if the signal to the TCM is inaccurate?
It can lead to poor shift quality, increased wear on transmission components, and potential damage over time.
Working a real vehicle right now?
Let DiagCoach walk you through it live with your specific symptoms, vehicle, and what you've already checked.
Start guided diagnostic →