Skip to content
US diesel $4.049 per gallonWeek ending Aug 17, 2026 · EIA
SemiTrucks.org
← All engines

Caterpillar C15

15.2 litre1999 to 2010EGR (2004)

Caterpillar's last on-highway engine before it left the truck engine market in 2010 rather than build an SCR system. The pre-ACERT single turbo builds are the sought-after ones; the ACERT twin turbo builds are not.

Output

435-625 hp

1550-2050 lb-ft peak torque

Fuel per mile

$0.675

at 6.0 mpg and $4.049 a gallon

Fuel a year

$80,980

over 120,000 miles

In-frame overhaul

$18k-$28k

rough, and shop rates move it

In the exhaust

None before 2007, then ACERT with DPF

Exhaust gas recirculation arrives: some exhaust is fed back into the intake to cut oxides of nitrogen. It raises cylinder pressure and heat, and it introduced the EGR cooler as a thing that fails.

Known issues

ACERT builds are known for turbo, valve actuator and head problems and are the reason Caterpillar's on-highway reputation ended where it did. Pre-2004 units are a different and much better engine.

Verdict

A 3406E or an early C15 is a fine old truck engine. A 2007 to 2010 ACERT is the one generation of any make this reference would steer you away from most firmly.