If you’re dealing with fault codes 1664, 1691, 1922, 2692, 3256, 3376, 3396, or 4449 on your Cummins X15 CM2350 X114B or X15 CM2350 X116B, there’s a good chance your DOC baffle is broken—and that means trouble. Regens keep failing, soot builds up, and eventually, your truck goes into derate.

Cummins even released a Technical Service Bulletin (TSB180046) confirming that welding issues inside the DOC can cause baffle breakage, leading to major aftertreatment failures. Their solution? Replace the entire DOC—which isn’t cheap.

But here’s the good news: DPF Guys can repair your DOC and get it back to you fast—without the high cost of a replacement. Just ship it to us, we’ll fix it, and send it back within a few days.

What is the DOC Baffle & Why Does It Matter?

The Diesel Oxidation Catalyst (DOC) is the first stage of your aftertreatment system. Its job? To oxidize carbon monoxide (CO), hydrocarbons (HC), and convert nitric oxide (NO) into nitrogen dioxide (NO₂)—which is needed to burn off soot in the DPF.

Inside the DOC, a baffle helps direct exhaust flow evenly across the catalyst.

When that baffle breaks, exhaust flow is disrupted, causing:

• Poor NO₂ production → No passive regeneration
• Low heat generation → Failed active regens
• Excess soot buildup → DPF clogging & engine derates
• Frequent regens → Wasting fuel & downtime

In short? A broken DOC baffle will destroy your aftertreatment system if left unchecked.

What Are the Symptoms of a Broken DOC Baffle?

• Frequent regen failures (because the DOC isn’t generating enough heat)
• Soot overload & high backpressure (causing constant forced regens)
• Rattling noise from the DOC (loose or broken baffle inside)
• Poor fuel economy (wasting fuel on unnecessary regens)
• Engine derates (limp mode!) (if the DPF overloads with soot)

If you’re seeing these symptoms along with fault codes like 4449, 2692, or 1664, your DOC needs to be inspected ASAP.

Cummins TSB180046 Confirms the Issue

Cummins issued Technical Service Bulletin TSB180046 specifically for the X15 CM2350 X114B and X15 CM2350 X116B engines.

TSB Highlights:

• Welding defects inside the DOC can cause baffle breakage
• Broken baffle leads to regen failures & excessive soot buildup
• Cummins’ solution? Full DOC replacement (which is expensive)
• Recommended fix: Inspect DOC inlet for damage & replace if broken

Read the official Cummins TSB180046 here: Broken Aftertreatment DOC Baffle – Cummins TSB180046

But instead of replacing it, DPF Guys can repair your DOC at a fraction of the cost.

How DPF Guys Can Fix It Fast

Cummins says your only option is to replace the DOC—but that’s not true. DPF Guys can repair it and send it back within days.

How It Works:

1. Ship your DOC to us – We’ll inspect it and confirm the failure.
2. We repair the baffle & restore function – No more uneven exhaust flow!
3. We test it to ensure it works like new.
4. We ship it back—FAST.

Get your DOC back and get back on the road in days, not weeks.