Earlier this week we covered dyed diesel on the highway. Texas now has a second fuel change, and this one can hurt modern trucks.
On October 5, EPA granted Texas an emergency fuel waiver that allows diesel with up to 500 ppm sulfur to be produced and sold in the state. Normal highway diesel is capped at 15 ppm. If your fleet runs Texas lanes, here is what matters.
What the Texas diesel fuel waiver does
At Governor Abbott’s request, EPA temporarily waived the federal ultra-low sulfur diesel (ULSD) standard and the Texas Low Emission Diesel (TxLED) rules. It applies only in Texas.
The waiver runs October 5 through October 24, 2026, the 20-day maximum the Clean Air Act allows. EPA says it stands ready to extend it if supply conditions warrant. As of October 9, no extension had been issued.
Fuel made under the waiver before it expires can be sold until it runs out, so higher-sulfur fuel could stay in Texas tanks past October 24.
Who can use it, and who can’t
Under EPA’s letter, the 500 ppm fuel is only for:
- Highway vehicles with engines built before the 2007 engine model year.
- Nonroad engines certified to Tier 1, Tier 2, or Tier 3.
It may not go in anything equipped with a diesel particulate filter (DPF) or catalytic emission controls, such as SCR. Tier 4 nonroad engines must stay on ULSD. EPA notes that many 2007 model year trucks have 2006 engines, so check the emissions label on the engine, not the title.
Sellers must give buyers EPA’s warning, which says anyone using the fuel assumes all responsibility for damage.
What the OEMs are saying
Cummins told CCJ it still recommends customers follow the fuel specifications for their engines:
Failure to use the approved fuel (maximum 15ppm sulfur diesel fuel for Tier 4 and 2007 and newer engines) can damage the engine and aftertreatment system.
Cummins, statement to CCJ
Failures caused by incorrect fuel will be denied warranty coverage, Cummins added, as Overdrive also reported. International told CCJ that damage from fuel not meeting EPA requirements and ASTM D975 ULSD specs “may affect warranty coverage.” Daimler Truck North America said fuel must meet its guidelines, including ASTM D975.
Where dyed diesel fits
These are two separate changes. Texas suspended its state limits on dyed diesel on highways September 28, though the 20-cent state tax is still owed. EPA’s waiver is about sulfur and TxLED. It does not mention dye.
Color tells you tax status, not sulfur content.
What fleets on Texas lanes should do now
- Check pump labels. Look for the EPA warning or anything other than 15 ppm ULSD before fueling a 2007 or newer truck.
- Keep fuel receipts. If a warranty question comes up, you will want the record.
- Train drivers. Brief anyone fueling in Texas this month.
- Watch the aftertreatment. Note new DPF, SCR, or NOx sensor codes and any change in regen frequency. Do not wait for a 5 MPH derate.
- Scan early. If a truck may have taken the wrong fuel, pull codes and check aftertreatment data before the next run.
With 2027 engines arriving under tighter NOx rules, ULSD-only aftertreatment is not going anywhere. Catching a problem early is cheaper than finding it on the shoulder.
Quick answers
Can my 2007 or newer truck use the 500 ppm diesel?
Not if it has a 2007 or newer engine. Anything with a DPF or catalytic emission controls must stay on 15 ppm ULSD.
When does the Texas diesel fuel waiver end?
October 24, 2026, unless EPA extends it. As of October 9, it had not been extended.
Is red-dyed diesel the same as the 500 ppm fuel?
No. Dye marks tax status. EPA’s waiver covers sulfur. Check the label, not the color.
Will warranty cover damage from the wrong fuel?
Cummins told CCJ that failures caused by incorrect fuel will be denied warranty coverage. Check your OEM’s terms.
Scan before it becomes downtime
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