Transmission shift solenoids operate by receiving an electrical signal from the ECU which causes an internal plunger mechanism to regulate the flow of pressurized transmission fluid through the system at a certain point. A P0758 code suggests that there is an electrical problem with one of the solenoids, and it is not allowing fluid to flow, which will cause a slew of problems.
When the code P0758 is set it simply means that the ECM or PCM is not able to properly see the specified RPM change that occurs during a 2 – 3 shift. A P0758 also suggest that the computer is not seeing the correct increase in road speed from the vehicle speed sensor.
How Serious is a P0758 Code?
A P0758 DTC means that the engine or transmission control module is not completely capable of controlling of shift solenoid ‘B’. This often results in drivability issues, such as engine stalling and shutting off..
P0758 DTC Symptoms
The tell tale signs that you may be experiencing a P0758 issue often include symptoms such as:
- Limp mode
- Harsh or erratic shift characteristics
- Transmission slipping or lazy shifting
- Engine stalling
- Vehicle won’t move
- Reduced fuel economy
- Transmission overheating & temperatures too hot
What Causes A P0758 Code?
There are a number of common causes of P0758 codes including:
- Low transmission fluid
- Dirty transmission fluid and / or filter
- Frayed wiring or damaged internal transmission wiring harness connectors
- Failing shift solenoid
- Failing transmission pump – not able to circulate transmission fluid properly
- Internal transmission pressure problems
- Valve body issue
- ECU or TCM failure
How to Diagnose P0758 Code
If your experiencing any of the common P0758 DTC symptoms, one of the first places to look at is the transmission fluid. If the transmission fluid contains any dirt, sludge or metallic debris, the shift solenoids typically won’t work as they should, causing issues.
Something else to look for is any metal shavings in the fluid. This is a common sign that there is more than likely an internal component or “hard part” failure.
Because the transmission fluid provides you with a lot of information on it’s own in regards to the transmission’s “health”, checking the ATF levels and condition needs to be the first thing you do when diagnosing a transmission solenoid fault code.
If the fluid is dirty as mentioned before, and there is a reduction in pressure due to any suspected blocks, then a full transmission service and flush may need to be done in order to remedy the situation.
If there is no sign of lack of maintenance, and the transmission fluid looks clean and red, then your internal transmission wiring and / or connectors should be checked. The first thing to look at in regards to the wiring is potential damage and / or corrosion inside the plug(s).
If everything checks out, your next step needs to be testing the shift solenoid. This needs to be done based on your vehicle manufacturer’s recommended procedure.
If there are no obvious issues have been found after these checks, then the problem could be caused by the transmission pump, valve body, or pressure regulator.
Common P058 Codes Diagnostic Considerations
When diagnosing a P0758 solenoid related DTC, it’s important to follow your vehicle manufacturer’s solenoid testing procedure. This will ensure you get accurate results with the test, and will prevent further damage.
One of the most common things to consider when diagnosing a P0758 code is the wiring. It’s not too out of the ordinary for the wiring to be faulty or going bad. In addition, be sure to check for any clogged internal fluid passages, as this can certainly cause P0758 related issues.
What Repairs Will Fix P0758?
- Changing the transmission fluid and filter (if applicable)
- Replace faulty shift solenoid
- Repair or replace a faulty transmission pump (if applicable)
- Repair or replace defective transmission valve body (if applicable)
- Perform transmission flush to clean passages
- Cleaning corrosion from connectors
- Repairing or replacing wiring
- Flash or replace PCM/TCM
- Install a rebuilt or remanufactured transmission (If applicable)
DTC Codes Related To P0758
P0755 – Shift Solenoid ‘B’
P0756 – Shift Solenoid ‘B’ Performance or Stuck Off
P0757 – Shift Solenoid ‘B’ Stuck On
P0759 – Shift Solenoid ‘B’ Intermittent