What Does P0849 Mean?
The TCM has detected an intermittent signal from the transmission fluid pressure sensor/switch "B" circuit. The voltage is randomly spiking, dropping out, or fluctuating in a pattern inconsistent with normal pressure changes. This typically indicates a connection problem rather than a complete component failure.
Common Causes
35%
Loose or intermittent connection at pressure sensor B
25%
Chafed or damaged wiring with intermittent contact
25%
Pressure sensor B developing intermittent internal fault
10%
Transmission fluid contamination intermittently affecting sensor
5%
TCM connector pin intermittent contact
Diagnostic Steps
1
Monitor the pressure sensor B PID in live data during driving for several minutes; document any sudden spikes, dropouts, or erratic fluctuations.
2
Perform a wiggle test on the sensor connector and associated harness while observing the signal for disruptions.
3
Inspect the sensor connector pins for corrosion, spread, or backed-out terminals.
4
Examine the internal transmission harness for damage or routing issues near vibration sources.
5
If connector and harness are sound, replace the pressure sensor B and retest.
Estimated Repair Cost
$200 - $850
Parts + labor, varies by vehicle and location
The TCM has detected an intermittent signal from the transmission fluid pressure sensor/switch "B" circuit. The voltage is randomly spiking, dropping out, or fluctuating in a pattern inconsistent with normal pressure changes. This typically indicates a connection problem rather than a complete compo...
The most common cause of P0849 (Transmission Fluid Pressure Sensor/Switch "B" Circuit Intermittent) is: Loose or intermittent connection at pressure sensor B
Typical repair costs for P0849 range from $200 to $850, depending on the vehicle, location, and whether you do it yourself or go to a shop.
The vehicle may experience occasional harsh shifts or brief slippage. Drivable but transmission behavior can be unpredictable. Diagnose and repair before the intermittent issue becomes a constant failure.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0849 to identify the root cause.
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Quick Info
Category
Powertrain
System
Automatic Transmission
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
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