Data Link - Engine Control Module (ECM) Communication Error
ECM is not communicating properly with other modules.
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 Control Module (ECM) isn't talking to the other vehicle systems correctly, which can cause performance issues or prevent the engine from starting.
What the computer is actually seeing
ECM shows no data exchange from one or more related controllers, indicating a communication fault.
What a healthy reading looks like
Data packet transmission must occur within 10 milliseconds; voltage at the communication lines should be around 2.5V to 5V during operation.
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 engine harness connectors for secure fit and signs of corrosion or damage. Decision: If damaged, repair/replace wiring or connectors; if not, proceed to step 2.
- 22. Test the voltage at the ECM communication pins with the key on and engine off. Expect 2.5V to 5V. Decision: If out of range, check for shorts to ground or power; if within range, proceed to step 3.
- 33. Perform a software update on the ECM and any related modules. Decision: If communication resumes, the issue is resolved; if not, proceed to step 4.
- 44. Inspect for DTCs in all relevant modules. Decision: If multiple DTCs, isolate fault to a specific module or wiring; if none, suspect ECM failure.
Common causes
- Damaged wiring or connectors in the communication harness
- Software issues in the ECM or affected modules
- Low power supply to the ECM
Typical repair cost
$$$
Related codes
Frequently asked questions
Is it safe to drive with this code active?
No, the car may enter limp mode or not start, potentially leading to unsafe driving conditions.
Will this code return after repairs?
If the underlying issue is not fixed, such as wiring or connector problems, it can return.
Why does this code sometimes pair with SPN 520173?
Both involve communication issues, often indicating a shared wiring problem or failure of the ECM.
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