Code Definition

P1870 — Automatic transmission slipping

System: Powertrain  |  Type: Manufacturer-Specific  |  Make: Acura

About P1870

P1870 is a manufacturer-specific powertrain diagnostic trouble code recorded for Acura vehicles. It belongs to the P-prefix family of codes, which covers engine, transmission, emissions, or fuel-system faults.

Scanning & clearing: A generic OBD-II scan tool will usually read and clear powertrain (P) codes. For live data, freeze-frame capture, and bi-directional tests you may need a more capable scan tool that supports the vehicle's ECM protocol.

P1870 is a manufacturer-specific code. The same code string on a different make may have a different meaning. Always confirm the code's definition against the vehicle's service information for the specific make and model under test.

Code Information

This code relates to mechanical transmission performance rather than a single circuit. The Powertrain Control Module (PCM) compares engine speed, turbine or input speed, and output shaft speed to evaluate how well the clutches, bands, and torque converter clutch are holding. DTC P1870 sets when the PCM detects excessive slip during gear engagement, often under steady throttle or during torque converter clutch application, with the slip exceeding calibrated thresholds over a defined period. This points to degraded hydraulic pressure, worn friction elements, or a control fault. The driver may no...

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