The EMD F40PH is a four-axle 3,000–3,200 hp (2.2–2.4 MW) B-B diesel-electric locomotive built by General Motors Electro-Motive Division in several variants from 1975 to 1992.

Amtrak retired its fleet of F40PHs in the early-2000s in favor of the GE Genesis, but the locomotive remains the mainstay of VIA Rail's long-distance trains; a depiction of the locomotive hauling The Canadian is featured on the reverse of the Frontier series Canadian $10 bill.

[2] Amtrak inherited an aging and mechanically incompatible fleet of diesel locomotives from various private railroads on its startup in 1971.

[4] Meanwhile, the poor truck design of the P30CH (and the electric GE E60CP) curtailed further orders of that unit when Amtrak found itself needing more short- and medium-distance power in the spring of 1975.

[8] On some later versions of the F40PH (and on many rebuilt F40s), a second small auxiliary diesel engine at the rear of the locomotive powers the HEP alternator.

[11] In the initial design the battery box and air reservoirs were located forward of the fuel tank.

The first event was a sharp decline in the mechanical reliability of the EMD SDP40F, including several derailments.

The second event was the unusually harsh winter of 1976–1977, which sidelined many of Amtrak's aging steam-heated coaches.

Amtrak suspended numerous routes and pressed the new HEP-equipped Amfleet I coaches, designed for short runs, into service.

[8] As problems with the EMD SDP40F mounted, Amtrak adopted the F40PH as its long-term solution nationwide for diesel engine service.

The 40 rebuilt locomotives, designated F40PHR, were identical to new-build EMD F40PHs, incorporating the larger fuel tank and more powerful HEP generator which had become standard.

[23] The Panama Canal Railway acquired several ex-Amtrak F40PHs for both freight and passenger service; the 480V head-end power matched the voltage used by the refrigeration in Maersk Sealand containers.

[24] The EMD F40PH has continued to serve VIA Rail into the 21st century: between 2007 and 2012 VIA refurbished its entire fleet for CAD$100 million.

[1] The F40PH-2D, employed by Via Rail, had special customizations for operating in Canada, including ditch lights.

[31] Metra's last 30 locomotives, designated F40PHM-2 (now rebuilt as F40PHM-3), were built with a sloped cab similar to the experimental EMD F69PHAC.

"[30] Speno's four locomotives, designated F40PH-2M, were delivered without turbochargers, limiting power output to 2,000 horsepower (1,500 kW).

Colloquially known as "cabbages" (a portmanteau of "cab" and "baggage"), and officially known as Non-Powered Control Units (NPCUs), these units had their diesel engines, traction motors, and main alternators removed, as well as a large roll-up door installed in the side (allowing the former engine compartment to be used for baggage).

406 (later renumbered 90406) to an NPCU to enable push-pull operation of Amtrak's 40th-anniversary exhibit train; in addition, a HEP generator was installed to supply auxiliary power.

The F40M-2F, which runs on the San Luis and Rio Grande Railroad and formerly the Canadian American Railroad, was regeared for a maximum speed of 65 miles per hour (105 km/h) and given an enlarged 2,900 US gallons (11,000 L; 2,400 imp gal) fuel tank.

The orders for GO Transit and VIA Rail Canada were built by General Motors Diesel (GMD), the company's Canadian subsidiary.

[47][48] In October 2024, the Southern California Railway Museum began fundraising in hopes of preserving a non-rebuilt Caltrain F40PH-2 locomotive.