P0758

Shift Solenoid B Electrical

P0758 is a generic OBD-II powertrain diagnostic trouble code: Shift Solenoid B Electrical. It is logged by the engine control unit when the powertrain monitor detects that a specific fault threshold has been exceeded — typically resulting in the malfunction-indicator lamp (MIL / check-engine light) being illuminated.

Code
P0758
Group
Powertrain
System
Powertrain
Severity
high
Need P0758 disabled?
RaceTune permanently disables any OBD-II trouble code on supported ECUs — for motorsport, off-road, and export use.
→

What P0758 means

Code P0758 is stored when the Transmission Control Module (TCM) detects an electrical fault — typically an open circuit, short to ground, or short to voltage — in the control circuit of Shift Solenoid B. Solenoid B manages hydraulic pressure to the clutch packs governing the 2–3 gear transition. An electrical failure in this circuit means the solenoid cannot receive or act on the TCM's drive signal, so the commanded gear change cannot be executed. The TCM monitors the circuit continuously and flags P0758 the moment measured current or voltage deviates from expected values.

Unlike the hydraulic performance fault P0756, where the solenoid receives a valid signal but fails to respond mechanically, P0758 indicates the electrical signal itself is compromised. Common wiring faults include insulation chafed by heat or vibration exposing a conductor to ground or a voltage rail, corroded connector terminals increasing circuit resistance, and broken wire strands inside the harness causing intermittent open circuits that may only appear under flex or vibration. The solenoid's internal electromagnetic coil can also fail — developing a winding short or going open-circuit — which produces identical out-of-range readings at the TCM.

When P0758 is active, the transmission will usually enter limp or failsafe mode, locking into a fixed gear (commonly third) to protect the gearbox. Drivers will notice harsh or absent gear changes, elevated RPM at cruising speed, increased fuel consumption, and possibly engine stalling at low speed when the torque converter cannot decouple from the stalled drivetrain.

Accurate repair requires a wiring diagram and systematic electrical testing with a multimeter or oscilloscope. Replacing the solenoid without confirming the wiring harness and connector integrity risks repeated failure.

Common causes

Most-frequently reported root causes when P0758 is logged.

  • 1
    Faulty Shift Solenoid B coil (open or internally shorted winding)
  • 2
    Chafed, burnt, or broken solenoid signal wire causing open or short circuit
  • 3
    Corroded or damaged solenoid connector terminals
  • 4
    Low or contaminated transmission fluid causing solenoid overheating
  • 5
    Clogged transmission filter
  • 6
    Faulty transmission valve body
  • 7
    Blown fuse or damaged ground circuit for TCM/solenoid
  • 8
    TCM internal driver circuit failure
  • 9
    Water or fluid intrusion into the transmission wiring harness
  • 10
    Incorrect ATF type causing internal electrical component degradation

Symptoms drivers notice

Illuminated check engine light (MIL)
Transmission stuck in limp/failsafe mode
Harsh, erratic, or absent 2–3 gear shift
RPM flare or engine over-revving without corresponding vehicle acceleration
Transmission slipping or overheating
Increased fuel consumption
Engine stalling at low speed or when stopping
Delayed engagement when selecting Drive or Reverse

How to diagnose P0758

A typical diagnostic flow when this code is present.

  1. 1
    Connect a scan tool, read all DTCs, and record freeze-frame data; note vehicle speed, gear, RPM, and throttle position at the moment the fault set
  2. 2
    Inspect transmission fluid level and condition; replace and filter-change if degraded — this eliminates contamination as a contributing factor
  3. 3
    Visually inspect the transmission harness from TCM to Solenoid B connector for chafing, melted insulation, corrosion, or bent pins
  4. 4
    Measure Solenoid B coil resistance with a multimeter (typically 11–15 Ω; verify against manufacturer data); an open-circuit (OL) or out-of-range reading confirms solenoid coil failure
  5. 5
    Verify voltage supply and ground integrity at the solenoid connector with the ignition on
  6. 6
    Perform continuity testing on the signal wire between solenoid connector and TCM harness pin to detect any broken conductor
  7. 7
    If solenoid and full wiring circuit test within specification, perform TCM self-diagnostics per manufacturer procedure to assess internal driver stage integrity
  8. 8
    Replace only the components confirmed faulty; clear codes and complete a transmission road test across all gear ranges to verify repair

Related powertrain codes

Frequently asked questions

What is the difference between P0756 and P0758?

P0756 is a mechanical/hydraulic performance fault — Solenoid B receives a command but the transmission doesn't shift correctly. P0758 is an electrical fault — the TCM detects abnormal voltage or current in the Solenoid B circuit.

Can dirty transmission fluid cause an electrical code like P0758?

Indirectly. Severely contaminated or overheated fluid can damage solenoid coil windings over time, eventually causing them to short or open.

Is P0758 a serious fault?

Yes. An electrical failure in Solenoid B typically triggers limp mode, preventing normal gear selection and causing drivability issues. Continued driving risks clutch-pack damage.

Does P0758 always require solenoid replacement?

Not always. Damaged wiring or a corroded connector is equally likely. Install a new solenoid into a faulty harness and it will fail again quickly.

Could P0758 and P0753 appear together?

Yes. Both codes appearing simultaneously often indicates a shared wiring fault — such as a damaged harness section serving multiple solenoids — or a system-level issue like a failed TCM power or ground supply.

Disabling P0758 in software

RaceTune can permanently disable P0758 — and any other OBD-II diagnostic trouble code — on every ECU family we support. The monitor is disabled inside the ECU itself, so the fault stops being logged: the warning light stays off and the engine never enters limp mode for this code. The change is tied to your exact software version.

Permanent
The monitor is disabled in the ECU itself — not just cleared. It cannot return.
Tailored to your file
Each patch is matched to your specific software version — never a one-size-fits-all file.
Reversible
The original file is always preserved. Reflash the stock to return the ECU to factory state.

Software modifications affect emissions compliance and are not road-legal in many jurisdictions. RaceTune service files are intended for motorsport, off-road, and export use.

Got P0758 in your scan?

Upload your ECU file — we'll identify the exact software version and confirm whether a disable is available for your car.

Upload your file