01 What happens if you put petrol in a diesel engine? • 02 Mass Air Flow Sensor (MAF): How It Works, Symptoms and Prob… • 03 Car Security Systems: What They Are and How to Install Them • 04 The Heart of Your Car: How Does the Engine Actually Work? • 05 Volvo's Diesel Exit: A Sign of the Times or a Mistake? • 06 How A Weak Fuel Pump Can Cause Sudden Highway Stalls Withou… • 07 How Automatic Transmissions Decide When to Shift • 08 What are some of the most rare cars in the world? • 09 Why the 2025 Audi SQ5 Sportback Is a Serious AMG Rival • 10 C0000 - Vehicle Speed Information Circuit Malfunction •

DTC codes / P08xx · Transmission / P08BF

P08BFPressure Control Solenoid L Control Circuit/Open

P08BF indicates that the transmission control module (TCM) has detected an open circuit or excessive resistance in the control circuit for pressure control solenoid L, which is one of several shift and line pressure solenoids inside the transmission. The TCM commands a current to the solenoid and monitors the resulting voltage or current feedback; when the expected electrical response is missing, it sets this code and typically commands a fail-safe mode.

SystemPowertrain
Code typeGeneric (all makes)
SeverityMedium
Fix difficultyProfessional
AreaTransmission

Symptoms you may notice

  • Illumination of the check engine light or transmission warning light, often with no other noticeable symptoms
  • Harsh or delayed shifts, especially when the transmission is cold or under light throttle
  • The transmission may default to a fixed gear or fail-safe mode, limiting vehicle speed
  • Slipping or flaring during gear changes, particularly on the affected clutch or band
  • Rough engagement when shifting from park or neutral into drive or reverse
  • In some cases, the vehicle may enter limp mode and refuse to shift out of second or third gear

Common causes, most likely first

  1. Open or damaged wire in the solenoid control circuit, often due to chafing, corrosion, or a broken connector pin
  2. Faulty pressure control solenoid L itself, with an open internal coil or seized armature
  3. Corroded or loose electrical connector at the transmission pass-through or solenoid body
  4. Transmission fluid contamination or low fluid level causing solenoid overheating and winding failure
  5. Internal transmission damage, such as a cracked solenoid body or worn valve body bore, that interrupts the circuit
  6. A failed transmission control module (TCM) driver circuit, though this is less common than wiring or solenoid faults

How to diagnose and fix it

  1. Verify battery voltage and ground connections, then scan all modules for related transmission codes before focusing on P08BF alone
  2. Inspect the solenoid L circuit wiring and connectors for chafing, corrosion, or pushed-out pins, and repair as needed
  3. Measure the resistance of solenoid L at the transmission connector and compare it to the manufacturer's specification
  4. Check transmission fluid level and condition; service the fluid if it is contaminated or low, as this can cause solenoid faults
  5. If resistance is out of specification, remove the transmission pan and replace pressure control solenoid L, following the proper torque sequence
  6. After repair, clear codes and perform a relearn or adaptive drive cycle as required by the manufacturer
  7. If the code persists after solenoid and wiring repair, test the TCM driver circuit or consult a transmission specialist for internal inspection

What P08BF really tells you about solenoid L

  • P08BF is often set by a simple wiring issue rather than a failed solenoid, so always inspect the harness and connectors before condemning the solenoid itself.
  • A low or contaminated transmission fluid level can cause solenoid L to overheat and set an open-circuit code, so fluid condition is a critical first check.
  • Some vehicles use solenoid L for specific shift functions only, so the code may appear with no drivability symptoms until the vehicle reaches operating temperature or a particular gear.
  • The TCM may set P08BF intermittently if the solenoid coil is failing only when hot, so a resistance check on a cold transmission can miss the fault.
  • Replacing a solenoid without addressing a corroded connector or damaged wire will lead to a repeat code, so always perform a voltage drop test on the circuit.

Can I keep driving with P08BF?

You can usually drive the vehicle to a repair shop if the transmission has not entered limp mode, but avoid heavy acceleration, towing, or long trips because the transmission may shift harshly or slip. If the vehicle is stuck in a single gear or the warning light flashes, stop driving and have it towed to prevent further transmission damage.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

Running on fumes Free guides aren't free to make. Top up the tank. Any amount, one time. Fuel the Garage