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GTECH Calibration
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P1851

Brake Band Apply Solenoid Performance.

  • Saturn
  • Powertrain
  • Manufacturer code
  • Medium severity

How this code is built

P
SystemPowertrain
1
Defined byThe manufacturer
8
AreaTransmission
51
FaultThe specific fault in that area

What it means

P1851 on a Saturn means the transmission control module has detected a performance problem with the brake band apply solenoid in the automatic gearbox. The module commanded the band to apply or release and the resulting gearbox behaviour, such as slip or ratio change, did not match what it expected. Exact solenoid layout and which gear range is affected depend on the model and transmission fitted.

Symptoms

  • Transmission warning or check engine light on
  • Harsh, delayed or flared shifts
  • Slipping in one gear range or during engine braking
  • Transmission stuck in a limp-home gear
  • Poor acceleration or higher engine revs than normal

Possible causes

  • Faulty or sticking brake band apply solenoidlikely
  • Low, degraded or contaminated transmission fluidlikely
  • Worn or burnt brake band or internal clutch wear causing slippossible
  • Blocked transmission filter or restricted valve body passagespossible
  • Damaged wiring, internal harness or connector fault to the solenoidpossible
  • Faulty transmission control modulerare

How to diagnose

  1. Read all stored codes and freeze frame data, noting the gear, road speed and fluid temperature when the fault set
  2. Check transmission fluid level, condition and smell, following the procedure for the specific transmission
  3. Inspect the transmission wiring, connector and external harness for damage, corrosion, fluid ingress or chafing
  4. Check for other transmission, speed sensor or engine codes that could point to a shared cause
  5. Test the solenoid circuit resistance and supply against the manufacturer specification for that model
  6. Road test and watch live data for slip, commanded versus actual gear and solenoid duty cycle
  7. Drop the pan and inspect for debris or friction material, then check the filter, if the fluid is contaminated
  8. Check for a manufacturer calibration update only if a known bulletin applies to the vehicle

How to fix

  • Correct the fluid level or replace degraded fluid and filter as specified for the transmission
  • Replace the faulty brake band apply solenoid
  • Repair or replace damaged wiring, connectors or the internal harness
  • Clean or overhaul the valve body if passages are blocked or sticking
  • Overhaul or replace the transmission if the band or clutches are worn
  • Replace or reprogram the control module only after the wiring and solenoid are proven good

Can I keep driving?

Medium severity

Short, gentle driving to a workshop is usually possible, but slipping can quickly damage the transmission, so get it checked soon. Stop driving if the gearbox slips badly or will not select a gear.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.

This code for other makes

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