P0CA9 Code:

OBD-II Diagnostic Powertrain (P) Trouble Code

Possible Cause

To know real cause of P0CA9 based of if this code is present in your two-wheel drive vehicle, suspect a faulty PCM or programming error. In most four wheel drive applications the four-wheel drive switch is used to switch between two and four wheel drive operation, as well as between low and high ranges

Common Symptoms

  1. As exhaust gas temperature increases, the level of resistance in the sensor decreases, allowing the feedback voltage signal to the PCM to increase
  2. A suitable OBD-II scanner (or code reader) and a digital volt/ohmmeter will be most helpful in performing a successful diagnosis
  3. Several tools will be instrumental in successfully diagnosing this code
  4. Check local, state, and federal laws before removing emission related components.

Similar Problems

Transmission
BBV Sensor Circuit Low Voltage
TFP Valve Position Switch-Drive Without Drive Ratio

P0CA9 Troubleshooting

If this is the case with the code, you will be hearing very loud noises, like explosions, from the rear of the vehicle upon acceleration. Firstly check the carburetor to ensure that the fuel and air combination are properly balanced. If these settings are correct, then thoroughly inspect the distributor cap for any cracks or hairline splits, as this can produce a backfire. Move on to the spark plugs and ensure that they are clean and undamaged and inspect the engine gaskets for any sign of damage, as they are responsible for ensuring the correct gas exchange within the engine. P0CA9 OBD2 reports a sensor fault, replacement of the sensor is unlikely to resolve the underlying problem. The fault is most likely to be caused by the systems that the sensor is monitoring, but might even be caused by the wiring to the sensor itself.

How to turn off P0CA9 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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