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Category 10 of 12

Exhaust & Emissions

Catalytic converters, oxygen sensors, EGR valves, manifolds and exhaust hardware to General Motors original specification.

Emissions components have to satisfy the engine control module as well as the regulator. A catalytic converter with a lower precious metal loading will light off later and store less oxygen, and the module's catalyst monitor will eventually report efficiency below threshold even though the vehicle drives normally. Oxygen sensors must match the original heater circuit resistance and switching speed. We supply emissions components to the original GM specification so the on-board monitors run and complete as designed.

How exhaust gas is treated

1 Exhaust Manifold collects 2 Upstream O2 mixture feedback 3 Catalytic Converter converts 4 Downstream O2 checks efficiency 5 Muffler reduces noise 6 Tailpipe exit
Schematic view — component order shown for orientation. Not a model-specific engineering drawing.

A converter rarely fails on its own. It is usually killed by an upstream fault, so replacing it without curing that fault repeats the failure.

What we supply in this category

Symptoms that point to this system

Common complaints

  • A catalyst efficiency code returning after replacement
  • Sulphur or rotten-egg odour under load
  • A rattle from under the floor at idle
  • Failing an emissions test on readiness monitors
  • Reduced power with a restricted exhaust feel at high engine speed

Before you order

A converter almost never fails on its own. Replacing one without first correcting the misfire, oil consumption or rich condition that destroyed it guarantees a repeat failure, usually within months.

Vehicle coverage

We supply Exhaust & Emissions components across every General Motors division:

Questions we are asked about Exhaust & Emissions

Why did my new converter fail so quickly?

Because the cause was upstream. Unburnt fuel from a misfire or oil passing the valve stem seals will overheat and contaminate the substrate of any converter, original or otherwise.

Are upstream and downstream oxygen sensors interchangeable?

Rarely. They differ in heater circuit, wire length and often in element type, because their jobs differ — one controls fuelling, the other monitors the catalyst. Fit the part specified for the position.

Need this part identified?

Send the VIN and a description. We will identify the correct OE part and quote it back to you.

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