P139C Code:

OBD-II Diagnostic Powertrain (P) Trouble Code

Possible Cause

Common causes of P139C include a faulty electronic pressure control solenoid, hydraulic blockages inside the internal transmission fluid passages, mechanical internal transmission failures, low transmission fluid, dirty or contaminated transmission fluid, a faulty PCM or transmission control module.

Common Symptoms

  1. The sensor is supplied with a low voltage (usually 5-volts) power wire and a ground wire
  2. As the input shaft is turned (by the engine) the electro magnetic input/turbine speed sensor uses the spaces between the splines to provide voltage signal interruptions in the circuit
  3. A scanner (or code reader) and a digital volt/ohmmeter will be required to successfully diagnose this code. Virtually every vehicle (with an automatic transmission) produced since the mid-eighties is equipped with some type of computer controlled automatic transmission system
  4. Several tools will be instrumental in successfully diagnosing this code

Similar Problems

Fuel And Air Metering (Injector Circuit Malfunctions Only)
BBV Sensor Circuit Low Voltage
TFP Valve Position Switch-Drive Without Drive Ratio

P139C Troubleshooting

A sure sign of this is smoke or steam being emitted from underneath the hood. The ignition timing could be set incorrectly and will require adjustment. If, when looking under the hood, you notice that the drive belts appear loose, they need to be tightened or completely replaced. If there is a noticeable pool of fluid underneath the car, this could be a sign of the cylinder head gasket failing. That will be confirmed in the form of billowing smoke being blown from the exhaust system. P139C OBD2 may also be triggered by faults earlier down the line. For example, a dirty MAF sensor might be causing the car to overcompensate in its fuel-trim adjustments. As a result, oxygen sensors are likely to report fuel mixture problems.

How to turn off P139C check engine light ?

There are two ways to turn off the check engine light:

A repair technician can do so once repairs have been made.
The OBD II can automatically turn it off when it fails to detect the problem after several diagnostic cycles.

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