Transmission Fluid Pressure Sensor/Switch H Circuit Low
The P2857 code means the vehicle's onboard diagnostic system has detected: Transmission Fluid Pressure Sensor/Switch H Circuit Low. This is a moderate severity code.
- Keep driving?
- No — stop driving
- DIY difficulty
- hard
- Estimated cost
- $200 - $900 (parts and labor)
Read and clear transmission codes. Many trans codes are caused by low or burnt fluid -- check level and color before assuming the worst.
Basic scanners only read engine codes. This reads transmission, ABS, and airbag too.
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What Are the Symptoms of P2857?
- Soft or delayed shifts
- Transmission slipping under load
- Check Engine Light on
- Poor acceleration response
What Causes P2857? (Most Likely First)
- Short to ground in sensor H circuit Very High
- Failed pressure sensor H High
- Low transmission fluid level Moderate
- TCM ground circuit fault Low
Can I Still Drive with P2857?
No — stop driving. P2857 is rated moderate severity. Continuing to drive in this state risks further damage — get it looked at before your next trip.
Frequently Asked Questions
Why does low pressure cause slipping?
Low hydraulic pressure means clutches and bands cannot firmly engage, causing the transmission to slip during gear changes.
Can I add fluid to fix this?
If fluid is low, topping it off may temporarily help, but the sensor circuit issue still needs diagnosis.
Is driving dangerous?
Driving is not recommended as low pressure can cause further clutch and band damage.
Mechanics Guide Step-by-step diagnosis
How Do You Diagnose P2857?
-
Check transmission fluid level
-
Measure sensor H voltage at connector
-
Test wiring for ground shorts
-
Replace sensor and retest
Sources 1
This page is built from documented references. Verify against your own service info before repair work.
- SAE J2012Diagnostic Trouble Code Definitions (defines the generic OBD-II code ranges)
Which Vehicles Commonly Get P2857?
- 2010-2020 Toyota Camry
- 2012-2019 Honda Accord
- 2014-2020 Nissan Altima
- 2011-2020 Chevrolet Malibu
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