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P0726 OBD-II Trouble Code: Engine Speed Input Circuit Range/Performance

check engine light

P0726 code definition

The P0726 code means that the car’s computer has received an incorrect, irrational or erratic engine speed signal from the engine speed input circuit. Because of this, the transmission will not be able to shift correctly.

What the P0726 code means

The P0726 code is related to other similar codes dealing with the crankshaft position sensor and engine speed input circuit. Essentially, the car’s computer is receiving an incorrect signal from the engine speed input circuit. This signal might be erratic, outright incorrect, or irrational. The upshot is that the transmission cannot provide a shifting strategy because the computer is unable to determine the actual speed of the engine. The computer expects the engine speed to increase gradually, and if that does not happen, whether actual or due to a faulty signal, the P0726 code will be stored.

What causes the P0726 code?

There are multiple potential causes for the P0726 code. These can include:

  • A failed engine input speed sensor
  • A failed transmission output speed sensor
  • A short or open in the wiring harness to one of the sensors
  • A loose connection to one of the sensors
  • A faulty crankshaft position sensor
  • A faulty shift solenoid
  • Dirty, contaminated or low transmission fluid
  • Faulty PCM (rare)

What are the symptoms of the P0726 code?

A range of different symptoms could be present with the P0726 code. These can include the following:

How does a mechanic diagnose the P0726 code?

First, the mechanic should read the codes stored in the computer using an OBD II scanner. Often, the P0726 code is stored with other codes relating to the problem, which can help move the diagnosis along. After checking the code, it should be cleared and the vehicle test driven to see if the code will reset, and to test for operating problems.

Next, the mechanic should inspect the wiring and connector leading to the engine speed input sensor and the sensor’s circuit. Damaged wires should be replaced or repaired and any corrosion should be cleaned. Loose connections should be repaired, and then the vehicle should be tested again.

If a test drive results in recoding, the mechanic should check for reference voltage at the input speed sensor. Continuity and resistance should be checked in both circuits. If the sensor fails these tests, it should be replaced.

Common mistakes when diagnosing the P0726 code

The most common mistake here is assuming that the problem is the vehicle speed sensor and replacing it without further diagnosis. Other incorrect assumptions (made without a full diagnosis) include a problem with the fuel delivery system, a transmission failure or driveline problem.

How serious is the P0726 code?

The P0726 code is serious, and should be diagnosed immediately. It can result in serious drivability problems, up to and including the engine stalling while slowing to a stop in traffic. This can lead to accidents that could have been avoided. There is also the potential for damage to the transmission if it fails to shift correctly, or at all.

What repairs can fix the P0726 code?

The most common repair is the replacement of the engine speed input sensor, although corrosion and damage to connectors, wires and wiring harnesses are also common repairs needed. Replacing a defective transmission output speed sensor is also a common repair.

Additional comments for consideration regarding the P0726 code

Note that the Check Engine Light will not come on in all instances.

Need help with a P0726 code?

YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
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