I have a 1998 Buick Century Custom and I failed inspection for a P1870 code. What is this and how do I fix it? I was told to disconnect the battery for a few hours and this may reset it.


Asked by Sep 12, 2013 at 01:02 PM about the 1998 Buick Century Custom

Question type: Maintenance & Repair

1 Answer


DTC P1870 is a type B code. The conditions for setting the P1870 DTC must occur on TWO CONSECUTIVE TRIPS (ignition cycles, with a drive cycle) before setting a P1870 history code. When the conditions for setting DTC P1870 are met (first trip), the PCM commands maximum line pressure and harsh 1-2 shifts are the result. This may result in a harsh 1-2 shift with no history code if the conditions for setting the DTC required for the second trip are not met, on two consecutive trips (Ignition cycles, with a drive cycle). When the conditions for setting the DTC are met, on the second consecutive trip, a DTC P1870 is stored as a history code. When the P1870 code is stored, the PCM will turn on the Service Engine Soon (SES), Check Engine Light (CEL), or Malfunction Indicator Lamp (MIL). Correction Install a control valve body with the revised TCC regulator and isolator valves. You can try the battery disconnect idea but if it does work it will be temporary.

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