The largest online repair guide library for every car

About us
Contact support
FAQ
Sign up
Sign in

2016 Canyon Diesel MPG Drop & Exhaust Smell

0

Mike T. · rep 0 · May 25, 2:36 AM · 1 replies · solved · Question

Vehicle: 2016 GMC Canyon Duramax SLT

Hey GMC owners,

I'm looking for some advice on my 2016 GMC Canyon Duramax diesel. Over the past few weeks, I've noticed a significant drop in my fuel economy, probably around 3-4 MPG less than usual. On top of that, there's a distinct exhaust smell, almost like raw diesel, coming into the cabin sometimes, especially when idling or at low speeds.

It's got about 110,000 miles on it, and I've kept up with all the regular maintenance. There's no check engine light on, which is confusing. The truck otherwise seems to run fine, no noticeable power loss or strange noises.

Could this be related to the DPF system, or something else entirely? Any other 2016 Canyon diesel owners experience this, and what was your fix?

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 25, 2:36 AM

0

ClearTheCode admin answer:

A drop in MPG combined with an exhaust smell in the cabin of your 2016 GMC Canyon Duramax is concerning, even without a Check Engine Light. Diesel engines have unique exhaust and emissions systems that can cause these symptoms.

Possible Causes:

  1. Exhaust Leak: The most likely cause of an exhaust smell in the cabin. Check for cracks in the exhaust manifold, exhaust pipes, or a faulty gasket between exhaust components. Leaks before the catalytic converter/DPF can also affect O2 sensor readings, leading to poor fuel economy.
  2. Clogged Diesel Particulate Filter (DPF): A DPF that is excessively clogged can restrict exhaust flow, forcing the engine to work harder, thus reducing fuel efficiency. While a DPF issue often triggers a CEL (P2002), it's possible for early stages to manifest as reduced MPG and unusual smells.
  3. Failing Oxygen (O2) Sensor or NOx Sensor: These sensors monitor exhaust gases. A faulty sensor can send incorrect data to the engine control module (ECM), leading to an improper air-fuel mixture and decreased efficiency. This might not always trigger a CEL immediately.
  4. Leaking Fuel Injector: A very slight leak from a fuel injector could cause a diesel smell, but usually this would also lead to rough idle or misfires, and potentially a CEL.
  5. EGR System Issues: Problems with the Exhaust Gas Recirculation (EGR) valve or cooler can affect combustion efficiency and sometimes lead to exhaust smells.

What to Check:

  1. Visual Inspection: Look under the hood and along the exhaust system for any visible cracks, soot stains, or loose connections. Pay close attention to the manifold and turbo area.
  2. Listen for Leaks: With the engine running, listen for a 'ticking' or 'hissing' sound from the exhaust system, which can indicate a leak.
  3. Scan for Pending/History Codes: Even without a CEL, a professional scan tool might reveal pending codes related to the DPF (e.g., P2463 - DPF Restriction) or O2/NOx sensors.

When to See a Shop:

  • As soon as possible. An exhaust leak can allow dangerous carbon monoxide into the cabin. A professional diesel mechanic can perform a smoke test to pinpoint exhaust leaks and diagnose DPF or sensor issues. Addressing these issues early can prevent more costly repairs and ensure your safety.
Menu

Help & account