P0728 - OBD Trouble Code

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The error code P0728 can be identified as Engine Speed Input Circuit Intermittent. This fault code would mean that the car’s computer has received an incorrect, irrational or erratic engine speed signal from the engine speed input circuit. Due of this, the transmission won’t shift properly.

Willing to learn more about this error code? The trouble code P0728 can be defined as Engine Speed input Circuit Malfunction. This trouble code is generic, which would mean that it can apply to all the vehicles which are equipped with the OBD-II or the vehicles which are made since 1996 up to the present. The specifications on the definition, the troubleshooting steps as well as repairs can always vary from one vehicle make to another.

What causes this problem with the Engine Speed Input Circuit Intermittent?

• Flaws in the valve body
• Some quirks in the crankshaft or camshaft position sensor
• Malfunctioning engine sensors, such as the engine temperature sensor, or other drivability sensors
• The wiring and/or connectors in the engine speed input circuit might be opened or shorted
• Faults in the shift solenoid

1. Engine Wiring Connectors - Do you remember when was the last time you got your car Engine Wiring Connectors checked up? A dirty Engine Wiring Connectors can cause a lot of issues like displaying P0728 code.
2. Oil Pressure Sender - Poor Oil Pressure Sender can cause a lot of difficulties, so why not get it replaced at time?
3. Engine Control Module - Are there some faults in your Engine Control Module? Don’t waste time and get them replaced or else P0728 code can turn up.
4. Powertrain Control Module - OBD Code P0728 can appear because of faulty Powertrain Control Module.
5. EGR Valve Gasket - Everything is fine with EGR Valve Gasket and still P0728 code triggering? Then you must get your EGR Valve Gasket checked.
6. Turbocharger - There can be some issues with the Turbocharger due to which you may see P0728 code appearing over and over again. Visit us to buy best quality Turbocharger online.
7. Automatic Transmission Sensor - A lot of issues can arise do to defective Automatic Transmission Sensor. Did you just see P0728 code flashing? Now you know the reason why it is appearing. Get it inspected and replaced on time.

You might be thinking that how would you diagnose these problems? We at Parts Avatar Canada would help you diagnose the major symptoms easily.

Common Symptoms

• Issue of automatic transmissions shifting harshly (limp-in mode)
• Failure in transmission shifting or it might shift erratically
• Inoperative or irregular speedometer/odometer
• Tachometer might not be working properly
• Transmission slippage or delay in the engagement

The repairs which you will have to do to correct this fault code are simply straightforward; you can surely pinpoint the necessary repairs on the basis of your diagnosis. Have a look at some common fixes:

• Restore the quirky shift solenoid
• Carefully flush contaminated transmission fluid and then you should refill with clean fluid
• Replace or repair a flawed valve body
• You can always replace or replace the damaged engine sensors, such as the engine temperature sensor, or other drivability sensors
• Make sure to replace the defective engine input speed sensor or transmission output speed sensor
• The shorted, damaged, or open electrical components within the engine speed circuit should be repaired or replaced as per the need
• It is very important to replace the quirky crankshaft or camshaft position sensor
• Restore the faulty electrical components within the crankshaft sensor circuit

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Here are some steps which you should follow in order to diagnose this fault code:

If you want to diagnose the P0728 trouble code, then you will need a diagnostic scanner, a digital volt/ohmmeter (DVOM), and a reliable vehicle information source. Check the condition and level of the transmission fluid before diagnosing an automatic transmission related code.

Step 1

The first and the foremost step is to inspect the automatic transmission fluid level and condition utilizing your vehicle information source, find the proper method for checking the transmission fluid level. While most OBD-II equipped vehicles have automatic transmission dipsticks/tubes, others do not. If the fluid level is not within specifications, inspect the transmission housing, lines, and cooler for leaks. After any leaks are repaired, refill the transmission according to manufacturer’s specs and recheck to make sure that no more leaks are present.

You must pay attention to the odour and condition of the transmission fluid. If the fluid smells excessively burnt, appears extremely black, or has a heavy metallic hue, it is safe to suspect that the transmission has incurred catastrophic mechanical failure. If this is the case, you may want to remove the transmission pan and check for excessive debris such as clutch material, metal, parts, etc.

If there is excessive debris in the pan, removal of the transmission and an overhaul (with a new torque converter) will likely be required. With no more leaks present and the transmission full of the recommended fluid, you are ready to visually inspect wiring and connectors for signs of corrosion, overheating, or other damage. Make repairs as per the requirement.

Step 2

The scanner should be used effectively. If there are no visibly damaged wiring harnesses or connectors, and the transmission is filled to the correct level with the recommended fluid, connect the scanner to the vehicle diagnostic port and retrieve all stored codes and freeze frame data. Writing this information down may prove helpful as the diagnosis moves forward. Should the P0728 be reset, reconnect the scanner to the vehicle diagnostic port. Now, carefully monitor the data display screen while test driving the vehicle. Narrow the scanner data display to include only pertinent data and focus on engine input speed. If it fluctuates inexplicably or varies greatly from engine RPM, suspect a defective engine input speed sensor or a damaged/worn reluctor ring.

Step 3

The next step would be to test the engine speed input sensor. After unplugging the electrical connector from the engine speed input sensor, consult your vehicle information source and follow testing recommendations (using the DVOM) to test the sensor. The engine input speed sensor is defective if it does not fall within specs. If it is within specs, go to the next step.

Step 4

Check the engine speed input sensor signal/circuit. Reconnect the engine speed input sensor and test the sensor signal by connecting the test leads (of the DVOM) to the signal wire and the sensor ground wire right behind the sensor connector. Use your vehicle information source and follow

manufacturer’s specifications while carefully looking for glitches/spikes in sensor signal voltage with the engine running and the transmission in park or neutral. If the sensor signal is acceptable, use the DVOM to test system circuits between the sensor connector and the PCM connector.

Common Mistakes When Diagnosing The P0728 Code

• The crankshaft position sensor might be faulty
• Failure in the powertrain control module
• Some quirks in the transmission control module
• Wiring problems