P085B OBD Error Code: Problem & Solutions

<<See All OBD Codes

Improper shifts and reduced fuel economy are the major setbacks for this kind of a problem. In extreme cases engine stalling and vehicle dying while slowing can prove to be crucial on road. All these are an indication of a problematic gear shift control module thus storing OBD code P085B in the PCM (powertrain control module) and the check engine light turning on.

The Engine Control Module (ECM), Powertrain Control Module (PCM) or Transmission Control Module (TCM) uses input from various sensors including the gear shift control module to verify the correct operation of the transmission and its components. Engine speed is often calculated against the transmission speed sensor to determine gear ratio and torque converter slip. If the calculation does not match the desired value, the Diagnostic Trouble Code is set and the Check Engine Lamp is illuminated. This often leads to delayed upshifts and downshifts along with delayed ignition and increased emissions.

What causes this problem with the Gear Shift Control Module "B" Communication Circuit Low?

• Low transmission fluid level
• Dirty transmission fluid
• Faulty Shift Solenoids
• Shift Solenoids harness is open or shorted
• Shift Solenoids circuit, electrical connection faulty
• Transmission mechanical problems
• Transmission hydraulic control circuit
• Affected Transmission Control Module
• Engine lean conditions due to vacuum leaks
• Blown glow plugs
• Powertrain Control Module failure

1. Automatic Transmission Solenoid - Faulty shift solenoid can be a main cause for gear 2 slipping and thus needs to be checked for and replaced.
2. Transmission Control Module - Faulty TCM will cause abrupt shifts and engine halts. Thus, check and replace the TCM for proper functioning of the system.
3. Automatic Transmission Sensor - Check for faults in the transmission control sensor and replace if needed. Buy new sensor from us!
4. Auto Transmission Torque Converter - In rare cases the transmission torque converter can also be damaged, immensely harming the transmission system. Buy new parts from us!
5. Automatic Transmission Connector - Faulty connectors can be a major problem for various parts not functioning properly as well as causing damage to the wiring connection. Thus, it is important to replace faulty parts now!
6. Engine Control Module - Faulty ECM leads to engine stalling or not starting, and check engine lights being on. Replace damaged ECM now!
7. Powertrain Control Module - PCM related issues can hamper the fuel delivery system and engine performance. Find all the Powertrain related parts with us.
8. Diagnostic Tool - You will need high grade diagnostic tools for correction of the OBD error code which is detected. Visit us today to grab amazing deals.
9. Ignition System Parts - Check for ignition timing and blown spark plugs, ignition coils and parts and replace it now!
10. Exhaust System Parts - Check for exhaust gaskets leaks and hardware issues and replace faulty components now!
11. Cylinder Head Gaskets - Check for leakages in head gasket and replace if found leaky. Buy new head gasket now!

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 P085B here:

Common Symptoms

• Check Engine Light illuminated (Malfunction indicator lamp)
• Delayed shift or not shifting into gears
• Transmission slipping
• Loss of fuel economy
• In some cases, there may be performance problems, such as dying when coming to a stop after driving on the freeway and/or misfire-like symptoms
• Faulty wiring and connector issue

Want to correct the Trouble Code P085B? Read these points mentioned below:

• Refill of Low transmission fluid level
• Dirty transmission fluid to be changed
• Faulty Shift Solenoids Replacement
• Repair or replace Shift Solenoids harness which is open or shorted
• Faulty Shift Solenoids circuit, electrical connection repair/replace
• Shift Control Module replacement
• Shift control solenoid wiring and harness replacement 

Parts Avatar Canada is here to solve all your issues related to car parts. We have stocked a wide range of best priced Transmission, Gear Shift Control Module, PCM, TCM, Intake Manifold, Engine Oil, ECU, Crankcase, Cylinder Head Gasket, Exhaust System 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 P085B code to be stored:

• A mechanic will first input an OBD-II code reader into the vehicle's computer in order to read and identify the trouble code.
• A hydraulic pressure diagram should be fed into the proper opening in the transmission system in order to take pressure readings directly from the source.
• The transmission fluid should be tested with a dipstick and checked for problems.
• Any diagnostic findings should be compared with the car manufacturer's default specifications in order to pinpoint abnormalities.
• Next, check for various components of ignition system like ignition coils, wires, glow plugs, spark plugs and hardware to check on ignition timing.
• If you notice smoke emitting from the exhaust, check for exhaust leaks leading to lean engine condition, which will cause affected engine performance. Replace faulty connector, gaskets, and headers immediately.
• If there are other trouble codes registered on the OBD-II reader, it may offer additional guidance in finding the root problem.

Common Mistakes When Diagnosing the P085B Code

Oftentimes the PCM sensor and circuit is blamed, and replaced, without checking the circuit as well as neglecting the damaged wiring and connectors. Because there can be several causes for this code, a complete inspection should be carried out in order to avoid repairs that may be unnecessary and more expensive.