1999 GMC Sonoma Repair and Maintenance
A guide to problems, costs, maintenance and repair for your 1999 GMC Sonoma
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1999 GMC Sonoma ProblemsCheck Engine Light With Code P1870
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.
A Loose or worn gas cap may cause Check Engine Light to illuminate.
The serpentine belt tensioner can fail; it may become noisy and/or the belt may jump off. Replacement of the failed tensioner will be necessary.
1999 GMC Sonoma QuestionsWhat can cause transmission to not go in gear (1 answer)
The truck does not overheat and it runs ok. There are no codes in computer. Also coolant is new. Standard coolant. Not what came in the truck. Thanks