Engine Speed Signal Missing
The engine control module is not receiving a valid engine speed signal.
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) is supposed to get a signal that tells it how fast the engine is spinning. If it doesn't get this signal, it throws this code.
What the computer is actually seeing
The ECM expects to see a pulse signal from the crankshaft or camshaft position sensor that correlates to engine speed. It looks for specific voltages and frequency patterns, usually around 0-5 volts depending on the sensor type, within certain engine RPM ranges.
What a healthy reading looks like
Engine speed signal expected between 0-5 volts with distinct pulse patterns indicating RPM; frequency should correspond to engine speed (e.g., 1 pulse per revolution).
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 connections at the crankshaft and camshaft position sensors. Decision Point: Repair any issues found or continue checking.
- 22. Use a multimeter to test the crankshaft position sensor output. You should see a pulsing signal between 0-5 volts while cranking the engine. Decision Point: If no signal, replace the sensor. If a signal is present, continue checking the ECM.
- 33. Inspect the wiring harness from the crankshaft sensor to the ECM for continuity and resistance. Expected resistance should be below 5 ohms. Decision Point: If resistance is high or broken, repair the wiring; if wiring is good, proceed to checking the ECM.
- 44. Check the ECM for any stored codes and confirm it's functioning properly. Make sure all grounds are intact. Decision Point: Replace the ECM if it's faulty after all checks.
Common causes
- Faulty crankshaft position sensor
- Wiring issues in the engine speed circuit
- Faulty camshaft position sensor
- ECM malfunction or software issue
Typical repair cost
$$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It may be drivable, but performance could be affected significantly, and sensors not working might lead to further issues.
Will this code come back after clearing it?
It can return if the underlying issue isn't fixed; if the sensor or wiring is faulty, it will likely reappear.
Why do I see this with other codes?
This code often pairs with other engine sensor faults due to shared circuits or related failures.
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