P0998 OBD Error Code: Problem & Solutions

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OBD code P0998 can be defined as Shift Solenoid F Control Circuit Low. The major function of the solenoid is to control the automatic transmission fluid flow to help in shifting of the transmission. These solenoids are known as the electro-mechanical "pistons". There are a lot of shift timing solenoids included in the system.

Because the TCM can no longer control Shift Solenoid F, one or more gears may not be accessible in “D” mode, which means that you will encounter drivability problems. Specific drivability problems depend entirely on how the manufacturer decided to use SSF (Shift Solenoid F). If SSF is used for one of the brakes, for example, two or more gears may be locked out, so you may experience poor acceleration (taking off in 2nd or 3rd gear) or high-revving before shifting (taking off in 1st gear and shifting into 5th). If the SSF is used for a pressure regulator or torque converter lockup, then the effects may be slightly less noticeable, such as harsh shifting, slow engagement, or poor cruising fuel economy (both from a free torque converter and from the ECM running in open loop).

Depending on your specific automatic transmission failsafe design, you may be able to manually shift into 1st or 2nd gear by putting the shift lever in “L” or “2” position.

What causes this problem with the Shift Solenoid "F" Control Circuit Low?

• Broken connector
• Quirky powertrain control module
• Dirty or clogged transmission filter
• Malfunctioning transmission valve body
• Confined hydraulic passages
• Defective wiring
• The fluid level might be inadequate
• Issue of dirty or contaminated fluid
• Internal damage in the transmission
  Unusable shift solenoid 

1. Automatic Transmission Filter - The P0998 code can also arise due to some issues in Automatic Transmission Filter. So it is advised to replace them as soon as possible.
2. Auto Transmission Shift Solenoid - Do you remember when was the last time you got your car Auto Transmission Shift Solenoid checked up? A damaged Auto Transmission Shift Solenoid can cause a lot of issues like displaying P0998 code.
3. Powertrain Control Module - Powertrain Control Module is an important car part which should never be neglected. May be there is some fault in it due to which P0998 code may start flashing.
4. Automatic Transmission Fluid - Is your Automatic Transmission Fluid damaged or broken? Don’t worry as we have solutions for all your problems.
5. Automatic Transmission Valve Body Kit - Defective car Automatic Transmission Valve Body Kit can be a major reason P0998 code depicts. So make sure to replace it online so that you don’t have to face any further issues.
6. Engine Wiring Harness - Everything is okay with the PCM and still OBD code P0998 triggering? Then there must be some defects in Engine Wiring Harness. Replace them as soon as possible.
7. Body Control Module Component - Body Control Module Component is an important auto part. Take care of it and you can rely on us for best quality Body Control Module Component online.

It is vital to know the symptoms of an issue as only then you would be able to solve the problem. So that’s why we have listed out some major symptoms of OBD Code P0988 here:

Common Symptoms

• Inconsistent shifting
• Faulty acceleration
• Decrease in the overall performance
• Transmission skipping
• Fastened in gears
• Unskilful shift timing
• Unsatisfactory driveability
• Rigid or grating shifting 

Want to correct the Trouble Code P0998? Read these points mentioned below:

• Repair or replace the quirky transmission fluid
• Rehabilitate the defaults in the shift solenoids
• Add/replace transmission fluid
• Repair faulty electrical components in the internal transmission
• Restore the flawed PCM and TCM
• Carefully adjust the faults in the hydraulic blockages

Parts Avatar Canada is here to solve all your issues related to car parts. We have stocked a wide range of best priced Transmission Shift Solenoid, Shift Solenoid Valve, Transmission Control Module, Powertrain Control Module, Engine Control Module, Transmission Fluid and a lot more to help you out in fixing your car.

It is essential to diagnose this fault code. Here are some steps which a mechanic should follow for diagnosing the problem that triggered a P0998 code to be stored:

• You will require some important things like a diagnostic scanner, a digital volt/ohmmeter, and a reliable vehicle information source to diagnose a code P0998. Check for technical service bulletins which pertain to the vehicle, symptoms, and codes.
• You must change you fluid if it is grimy, smells burnt, overfilled and unusual colour. If you've owned your vehicle for 30,000 to 60,000 miles and you do not remember when was the last time you changed you fluid or have any records of it, not only may this be your issue, but you should follow your maintenance schedule to avoid this situation.
• Former fluid is mucky fluid, grimy fluid can cause blockages and blockages can be a big reason why this fault code is appearing so you must change your fluid. The manufacturers recommended steps should be followed properly when you are inspecting ATF. This basic step can differ a meaningful amount between the models as well as makes.
• The fluid is in nice condition, code is still present and symptoms exist? It all depends upon your specific model, the shift solenoid may be accessible externally. Now if you find out that this is the case, then you should check the solenoid and its harness/connectors to find out the signs of defect.
• All the issues should be repaired or replaced as per the need. It would be helpful if you will have a peak for any leaks as well. If your shift solenoid is internal, then you should attempt to access it, work around it for now. Exhaust other avenues, internal transmission diagnosing and repairing should be left to a certified technician.
• The TCM and harnesses involved in this circuit may be subject to rasping road conditions so make sure everything is complete in all aspects.
• After that the shift timing solenoid should be inspected. You may be able to test the solenoid itself multiple ways. One test may include a resistance test where you use a multimeter to measure the resistance between the pins in the solenoid to verify to a degree its electrical integrity.
• Then the other would include manually applying voltage to the solenoid to verify its mechanical operation. You should specify either one in your manufacturers’ service manual/technical literature.
• The circuit from the TCM should be tested properly. Then check the functionality of the sensor and its circuit by performing the same tests as above but from the pins at the TCM and/or ECM. This trick would be very helpful in verifying the integrity of the solenoid as well as electrical integrity.

Common Mistakes When Diagnosing The P0998 Code

• Defaults in the transmission shift solenoid
• Wiring related issues
• There can be a failure in the transmission control module
• Diminishing transmission fluid level