GMC Safari Problem Report

GMC Safari Check Engine Light With Code P1870

(12 reports)

Vehicles equipped whit a 4 speed automatic transmission may develop a harsh 1-2 shift and/or illumination of the Check Engine Light with code P1870 stored. This can be caused by wear of the bore for the TCC isolator and regulator valves in the valve body. This condition does not commonly occur until the transmission reaches normal operating temperature. If the valve body is worn, replacement will be necessary to correct this concern.

replaced valve body -
Check engine light wont go off tune up changed oil -
code just came on it does it only going over an overpass or normal operating temp. -
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