P0119

P0119 sets when the ECT signal jumps or drops out erratically rather than failing cleanly high or low. Cheapest-first and almost always correct on this code: wiggle-test. With the engine warmed up and the scan tool graphing ECT live, grab the connector and tug each wire while watching for a glitch. A clean sensor shows a smooth descending curve from cold start; an intermittent ECT shows spikes or sudden drops to -40 F or +250 F lasting a fraction of a second. Backprobe the signal wire and flex the harness from the sensor back toward the PCM. Healthy reference points: roughly 2.5 to 3.0 V at 70 F (about 2-3 kohm), 0.5 to 1.0 V at 200 F (about 150-250 ohm), and a continuous smooth curve between them on a warm-up graph. Caveat: thermal expansion of a marginal solder joint at the PCM connector or a splice pack can make this fault appear only after 20 minutes of driving; a 5-minute test in the bay will miss it.

Vehicle-specific patterns: 1999-2007 GM 4.8/5.3/6.0 LS trucks are the textbook case: the under-intake engine harness corrodes at the splice pack and the ECT signal drops out intermittently. 2003-2010 Dodge Ram 5.7 Hemi sees pushed-back terminal pins in the ECT connector that lose contact on rough roads. 2004-2010 Ford F-150 5.4L 3V has chafing on the ECT lead where it routes past the intake. 2002-2008 Honda Pilot/Odyssey J35 has TSB for an intermittent ECT connector seal failure that admits moisture. Estimated repair: $40 to $350.