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P0727 — Engine Speed Input Circuit No Signal

Generic OBD-II · all makesPowertrain (engine & transmission)

The PCM detects no signal from the engine speed sensor circuit, typically the crankshaft position sensor.

Symptoms

What causes it — most likely first

1. Crankshaft position sensor failure

The sensor can degrade or short out, eliminating the speed signal the PCM expects.

2. Wiring or connector problem

Corroded, damaged, or loose wires and connectors in the sensor circuit can interrupt the signal.

3. Ignition switch or related circuit fault

A fault in the ignition switch or the circuit feeding the sensor may cut power to the sensor.

4. Powertrain control module (PCM) fault

A PCM failure can cause loss of the sensor input circuit, but this is uncommon and usually accompanied by other PCM-related codes.

How it's diagnosed

  1. Inspect the crankshaft position sensor wiring and connectors for damage or corrosion
  2. Measure sensor resistance and check for proper voltage at the sensor's power supply
  3. Test sensor output signal while cranking the engine using a scan tool or oscilloscope
  4. Verify PCM power and ground circuits and check for blown fuses
  5. Replace the sensor or repair wiring as needed before considering PCM replacement

Code facts & related codes

SystemPowertrain (engine & transmission)
StandardizationSAE generic — identical on every make
Related codesP0720 — Output Shaft Speed Sensor CircuitP0721 — Output Shaft Speed Sensor Circuit RangP0722 — Output Shaft Speed Sensor Circuit No SP0723 — Output Shaft Speed Sensor Circuit InteP0724 — Brake Switch B Circuit HighP0725 — Engine Speed Input Circuit

Frequently asked

Will replacing the PCM always clear P0727?

No; most often the code is caused by a faulty sensor or wiring, and replacing the PCM does not resolve the issue.

Can a bad battery cause this code?

A severely low voltage can affect sensor operation, but the code is specifically tied to the sensor circuit.

Is the crankshaft position sensor covered under emissions warranty?

Coverage varies by manufacturer and jurisdiction; many vehicles have extended sensor warranties.

Do I need a dealer to diagnose this code?

Any qualified technician can diagnose it; a dealer is not required.