OBD-II Diagnostic Trouble Code
P0758 — Shift Solenoid B Electrical
P0758 indicates an electrical fault in the shift solenoid B circuit. The TCM monitors the circuit voltage or current while driving the solenoid and has detected an open, short to ground or short to power. It is a circuit-level fault, not a hydraulic performance fault.
Severity 4/5
Truck-relevant
Stop within 50 mi
Severity
Stop within 50 mi
Shift Solenoid B Electrical
Code
P0758
Category
Powertrain
Subsystem
Transmission
Truck-relevant
Yes
What this means for truckers
Stop within ~50 miles on a Cummins X15, Detroit DD15, PACCAR MX-13. Driving longer risks damaging adjacent components (turbo housing, head gasket, aftertreatment) and turning a $300 fix into a $3,000 fix.
Before you replace parts — try this first
P0758 on the Transmission system is most often damaged, chafed or corroded wiring or connector at the transmission case or tcm — not a dead part. On commercial diesels especially, work these in order before spending money on parts:
- Confirm the symptoms. Match what your truck is doing to the Symptoms section below. If the code is set but the symptoms are not there, clear the code and re-test after a drive cycle — it may not return.
- Clean and dry the sensor connector. Water, road salt, or oil seeping into a connector is the #1 fake sensor failure. Disconnect, look for green corrosion or moisture, spray with electrical contact cleaner, dry, reseat. Many faults clear here for $0.
- Inspect the wiring harness. Trace the wire from the sensor toward the ECM — look for chafing against the engine block, melted insulation near the turbo or exhaust, or pinch points where a clamp has rubbed through.
- Test the sensor before swapping it. Most Common Causes (below) list the expected voltage or resistance range — a $20 multimeter saves a $300 sensor swap that does not fix the problem.
- Only then, replace the part. Use the OEM or a tier-1 aftermarket. Cheap sensors throw the same code in two weeks.
Symptoms
Usually the TCM drops into a fail-safe gear, so the truck may start out in a higher gear, refuse to upshift or downshift, and feel underpowered when loaded. Shifts can be harsh when the fault comes and goes. Warning lights and a stored transmission code are typical; intermittent wiring faults may only set over bumps or when hot.
Common causes
- CommonDamaged, chafed or corroded wiring or connector at the transmission case or TCM ($120–$500)
- CommonShift solenoid B coil open or shorted ($350–$1000)
- OccasionalInternal transmission harness or pass-through connector leaking fluid or damaged ($300–$900)
- RareTCM driver circuit failure ($900–$2500)
How to fix
Inspect the external harness and case connector for chafing, corrosion and fluid intrusion
When to use: First check, especially after recent chassis or transmission work
Measure solenoid B resistance at the case connector and compare to the service spec
When to use: To separate a coil fault from a harness fault
Check circuit continuity and shorts between the TCM and solenoid with the TCM disconnected
When to use: When the solenoid measures correct but the code persists
Replace the solenoid or internal harness, or the TCM only after wiring and solenoid test good
When to use: Once the failed component is isolated
Affects most
No specific vehicle pattern found in our complaint database. This code can appear on any vehicle that supports OBD-II diagnostics.
Related
- → Browse all DTC trouble codes
- → Decode a VIN to check codes for your truck
- → Owner-operator maintenance guides
- → P0700 — Transmission Control System Malfunction
- → P0701 — Transmission Control System Range/Performance
- → P0702 — Transmission Control System Electrical
- → P0703 — Brake Switch B Circuit
- → P0705 — Transmission Range Sensor Circuit Malfunction
Frequently Asked Questions
Can I drive with code P0758?
Drive with caution. P0758 is severity 4 — stop within ~50 miles. Most commercial diesel codes at this severity (turbo, fuel rail, transmission solenoid) can damage adjacent expensive components if left unrepaired. Get to a service location before highway-speed loads.
How much does it cost to fix P0758 on a commercial truck?
Total repair cost ranges $120–$2500 depending on the root cause. The cheapest fix is usually the first one listed below — Damaged, chafed or corroded wiring or connector at the transmission case or TCM — which is also the most common. On commercial trucks the cost is usually higher than passenger vehicles due to part availability and shop labor rates ($120–185/hour at most truck shops, vs $90–130 at general auto shops). DIY-capable fixes (sensors, hoses, filters) are at the low end; major component replacements (turbo actuator, high-pressure fuel pump, transmission solenoid pack) are at the high end. Always diagnose with a scan tool BEFORE replacing parts — guessing wrong on a $1,500 turbo actuator when the actual issue was a $30 boost hose is a common expensive mistake.
Will P0758 fail a DOT inspection?
P0758 typically doesn't fail an inspection on its own. Inspectors focus on safety items (brakes, steering, tires, lights, HOS). Transmission codes only become an issue if the truck has shifting problems severe enough to qualify as 'mechanical fitness' OOS. Fix to prevent escalation.
What's the difference between P0758 and related codes?
P0758 is closely related to: P0700 (Transmission Control System Malfunction), P0701 (Transmission Control System Range/Performance), P0702 (Transmission Control System Electrical), P0703 (Brake Switch B Circuit). These codes share the same subsystem (transmission) and often appear together. If you see this code, scan for the full code list — fixing the root cause usually clears multiple companion codes at once. If only P0758 is set without the companions, the issue is more isolated.
How do I prevent P0758 from coming back after a repair?
For P0758 (Shift Solenoid B Electrical), prevention centers on the transmission system. Service transmission fluid at the OEM interval (typically 150K–250K miles for HD autos). Don't skip the magnet/strainer inspection. After repair, perform an adaptive shift relearn with a scan tool (or drive 40+ miles for adaptive ECMs to relearn naturally).