DTC P0128 or Engine Will Not Reach Operating Temperature - keywords 4.8 5.3 6.0 cooling coolant heat HVAC LM4 L59 LQ4 MIL P0128 PIP3267 PIP3267A radiator SES temp

This PI was revised so the information could be viewed in the new SI format. Please discard PIP3267.

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Possible DTC P0128 or the engine will not reach operating temperature after a radiator replacement. Some replacement radiators may be missing a restriction orifice that is built into the right side radiator tank. The restriction orifice is molded into the nipple that feeds the radiator surge tank.

The engine may not reach operating temperature, or set dtc p0128 due to excessive coolant flow to the radiator surge tank.

If SI diagnostics have been completed for dtc p0128 and no problem was found, contact the customer, and check the vehicle history for previous radiator replacements. If the radiator was replaced for a cooling system concern, or replaced during a front end body shop repair, it may be missing the radiator surge tank restriction orifice. Remove the surge tank hose from the radiator and visually inspect the radiator tank nipple that feeds the surge tank. If the radiator is missing the surge tank restriction orifice there will be an increased amount of coolant flow to the surge tank. Excessive coolant flow may induce DTC P0128.\

If the radiator surge tank restriction is missing, the radiator needs to be replaced with the proper replacement radiator as listed in the GMSPO parts catalog.

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.