Transmission Fluid Pressure Sensor/Switch H Circuit High
The P2858 code means the vehicle's onboard diagnostic system has detected: Transmission Fluid Pressure Sensor/Switch H Circuit High. 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.
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Basic scanners only read engine codes. This reads transmission, ABS, and airbag too.
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Common Symptoms
- Harsh or firm shifts
- Transmission bang when engaging drive
- Check Engine Light on
- Possible overheating
Probable Causes (Ranked by Likelihood)
- Open circuit in sensor H wiring Very High
- Disconnected pressure sensor H High
- Corroded sensor H connector Moderate
- TCM reference voltage fault Low
Step-by-Step Diagnostic Procedure
-
Retrieve DTCs and freeze frame
-
Inspect sensor H connector
-
Test for open circuits
-
Verify TCM reference voltage
Frequently Asked Questions
Why do shifts feel harsh?
When the TCM sees a high pressure reading, it may reduce line pressure compensation, resulting in harsh engagement.
Can wiring cause this?
Yes, an open wire causes the signal to read high, making the TCM think pressure is higher than actual.
Should I check for a TSB?
Technical Service Bulletins exist for many vehicles regarding pressure sensor issues. Your dealer can check for applicable TSBs.
Sources
This page is built from documented references. Verify against your own service info before repair work.
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