Diagnostic Aids
After engine is started, engine coolant temperature should rise to approximately 194°F (90°C) and stabilize when thermostat opens. If engine is allowed to cool to an ambient temperature or overnight, coolant and MAT sensor resistance or temperature may be checked with a Scan tester. Both components should have the same or close readings with each other. Code 14B sets if Gray or Gray/Black wire is open. If code is intermittent, see TESTS W/O CODES article.