Fault code P0727 – engine speed input (RPM) circuit no signal

Fault code P0727 is called “Engine Speed Input (RPM) Circuit No Signal” but in different programs it may be called differently. This fault designation applies to all vehicles equipped with OBD-II.

Technical description and explained code P0727

Diagnostic Trouble Code P0727 means that the transmission control module (PCM) has detected a circuit fault with the engine speed sensor input signal. This type of code may be caused by an electrical problem.

Fault code P0727 – engine speed input (RPM) circuit no signal

This sensor may sometimes be referred to as an engine speed sensor or engine input shaft speed sensor. It is usually located in the transmission crankcase near the front of the primary shaft.

The operation of the sensor is based on the Hall effect. It is installed so that the toothed ring can pass in close proximity to its magnetic tip. The protruding areas of the teeth serve to electromagnetically close the motor speed input circuit, while the recesses between the teeth interrupt the circuit.

These fast interruptions form an electronic waveform that represents a certain frequency and degree of voltage. The waveform is recognized by the PCM as the input motor speed.

If the PCM does not see the corresponding motor speed input for a given period of time and under certain circumstances. Then error code P0727 will be stored and the malfunction lamp may illuminate.

In some cases, the Transmission Control Module (TCM) or Engine Control Module (PCM) may put the vehicle into a failsafe or emergency mode.

Symptoms of vehicle malfunctions

The main signal that an error P0727 has occurred is the Malfunction Indicator Lamp (MIL) is also known as the CheckEngine Light.

It can also be warning signs such as:

  1. The “Check engine” control lamp on the control panel will light up (the code will be stored as a fault).
  2. Other related trouble codes may also be present.
  3. Inoperative speedometer or tachometer, or malfunction.
  4. Faulty or emergency mode of operation.
  5. Transmission slipping or delayed engagement.
  6. Transmission does not shift or shifts erratically.
  7. Hard shifting of gears.
  8. Increased fuel consumption.

The error P0727 is quite serious because the conditions that led to its persistence may cause damage to the transmission.

Factors that can cause this error code

The error code P0727 can mean that one or more of the following problems have occurred:

  • Faulty engine speed sensor.
  • Damaged or worn crankshaft speed sensor ring.
  • Broken or shorted wiring or connectors in the engine speed sensor input circuit.
  • Excessive metal deposits on the sensor’s magnetic tip.
  • Low level or contamination of transmission fluid.
  • In rare cases, malfunction of PCM or TCM.

How to fix or reset OBD-2 code P0727

Some suggested steps for troubleshooting and fix the error code P0727:

  1. Read all stored errors with an OBD-II scan tool.
  2. Clear the errors and test-drive to find out if error P0727 appears again.
  3. If the code appears again, inspect the wires and connectors for damage.
  4. Check the level and condition of the transmission fluid.
  5. Test the engine speed sensor input circuit; if there is a problem, replace the sensor.
  6. Flash or replace PCM/TCM if necessary.

Diagnose and repair of problems

When diagnosing transmission related trouble code P0727, start by checking the condition and level of the transmission fluid. Also pay attention to the smell of the transmission fluid. If the fluid smells like garbage, looks very black, or has a metallic hue, a mechanical transmission failure has likely occurred.

If the transmission fluid level is low, check the transmission, lines and cooler for leaks and repair if necessary. Fill the transmission according to the manufacturer’s recommendations and make sure there are no leaks.

If there is a large leak of transmission fluid from the torque converter area, repair. This may require removal of the transmission, and after examining it, determine the extent of the repair.

Wiring check and testing

Once the transmission is filled with the necessary fluid and there are no more leaks, visually inspect the wiring and connectors for damage, corrosion, or melt. Once you have determined that there is no visible damage to the wiring or connectors, connect the scanner.

Retrieve any stored codes, make a note of this information because it may be useful as you move forward with your diagnosis. Remove the codes and test-drive the vehicle to see if error P0727 appears again.

If the error appears, reconnect the scan tool and observe the engine speed input on the data display screen. Perform a test drive on the car and note the engine speed input.

If the engine speed input differs greatly from the RPM, the engine speed input sensor is most likely faulty. Also, do not overlook a damaged or worn reactive ring.

Use a multimeter to check the motor input speed sensor. Look up the specifications in your vehicle information source and follow the test recommendations.

Also check the sensor magnetic tip for excessive metal deposits and the reactive ring for defects.

On which vehicles does this problem occur most frequently

Fault code P0727 can occur on different vehicles but there are statistics on which brands this occurs most often. Here is a list of some of them:

  • Audi (A4, A5)
  • BMW (X5)
  • Chevrolet
  • Daewoo (Nubira)
  • GMC
  • Hyundai
  • Jaguar
  • Kia (Picanto, Sorento, Sportage)
  • Opel
  • Saturn (SL2)
  • Volkswagen (Touran)
  • Volvo

Fault code P0727 can sometimes be found with other errors. The most common are the following: P0050, P0102, P0154, P0160, P0335, P0340, P0492, P0503, P0562, P0725, P0726, P0728, P1602, P1740.

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