Diagnosis & Repair
WARNING: This page is about a different car, the 2003 Toyota Tacoma. However, it is still accessible from the selected car via links, so may be relevant.
Using Toyota hand-held tester or scan tool, read FREEZE FRAME data. Freeze frame data records engine conditions when malfunction is detected.
Connect Toyota hand-held tester or scan tool to Data Link Connector (DLC3) at driver's side of instrument panel. See Figure. Turn ignition on and then turn hand-held tester or scan tool on and check for any other codes output (besides DTCs P0116 and P0125). If any other DTCs are set, troubleshoot those first. If no other DTCs are set, check cooling system thermostat, and replace if necessary. If thermostat is okay, replace ECT sensor. See ENGINE COOLANT TEMPERATURE SENSOR under ENGINE SENSORS & SWITCHES in REMOVAL, OVERHAUL & INSTALLATION - 4-CYLINDER article.