P0290

P0290 is the cylinder 10 injector circuit LOW fault — the PCM is commanding the cylinder 10 injector to open but the current ramp it sees during the injection pulse is below the expected threshold, which physically means either the injector winding has gone high-resistance or fully open, the injector driver in the PCM is failing on that channel, or the wiring between PCM and injector has high resistance or a partial short. Cylinder 10 only exists on V10 and V12 engines, which narrows the scope sharply. Cheapest-first ladder: (1) Confirm cylinder 10's physical location from the FSM — on a Hemi 6.4 V8 SRT this code shouldn't apply (only 8 cylinders), but on a Ford 6.8 V10 cylinder 10 is on the left bank rear and on the Audi/Lamborghini V10 it's on the right bank toward the rear. (2) Pull the injector connector and ohm out the injector — V10/V12 saturated-driver injectors typically read 12-16 ohms across the winding; peak-and-hold injectors read 1-3 ohms; anything reading infinity is an open winding (replace injector). (3) Probe the connector for proper power (battery voltage with key on) and proper PCM ground pulse — a noid light flashes during cranking if the PCM is firing the driver correctly. (4) Swap the cylinder 10 injector with an adjacent cylinder's injector (mind the index code on direct-injection systems — they must be re-coded after swap) and clear the code; if P0290 follows the injector to the new cylinder, the injector is bad ($80-300 part for Ford 6.8 V10, $400-900 for Audi/Lamborghini V10), if it stays on cylinder 10, the wiring or PCM driver is the cause. The expensive misdiagnosis: don't replace the PCM before measuring resistance across the injector winding and ohming the harness end-to-end — a Ford 6.8 V10 PCM is $800-1,400, and 90% of P0290 tickets are a $90 injector or a corroded sub-harness connector under the upper intake.

Vehicle-specific patterns: 2003-2010 Ford 6.8 V10 (E-450, E-550, F-450/550 Super Duty, Excursion, Class A motorhomes on the F-53 chassis) is by far the most common P0290 vehicle in North America — the injectors are buried under the upper intake plenum, the sub-harness inside the valley fails at the connector, and salt-belt vehicles see corrosion at the cylinder 10 connector first because of its position relative to the firewall pass-through. 2003-2018 Dodge/Ram Hemi 6.4 SRT (Charger SRT, Challenger SRT/Hellcat, Grand Cherokee SRT, Durango SRT) does NOT actually have a cylinder 10 — these are V8s, so a P0290 on a Hemi is almost always a misread or a generic code being thrown by an aftermarket scanner; verify the OBD label and engine spec before quoting. 2008-2014 Audi R8 5.2 V10 and 2004-2014 Lamborghini Gallardo 5.0/5.2 V10 set P0290 from injector failure at the rear-bank cylinders, where heat soak from the exhaust manifold cooks the injector electrical body — Audi/Lambo OEM injectors are $400-900 each and must be coded to the ECU after replacement. Estimated repair: $90 (single injector on Ford 6.8 DIY) to $1,800 (Audi/Lambo injector replacement with coding at shop).