Close-Coupled Converter and Catastrophic Engine Failure - kw 3.5 catalytic contaminated contamination crank damage diagnostics driveability DTC emissions exhaust inoperative intake internal LX9 light

When servicing the vehicle with the VIN you entered, the following diagnosis might be helpful if the vehicle exhibits the described symptoms.

The 2004 Chevrolet Malibu with the 3.5L V-6 (RPO LX9) is equipped with a new style of catalytic converter, technically known as the close-coupled catalytic converter. Each engine exhaust manifold bolts directly to a catalytic converter, providing quick catalyst warm-up resulting in lower tail pipe emissions earlier in the vehicle operating cycle. If a catastrophic engine failure were to occur (such as broken intake/exhaust valve or piston) debris may be deposited in the converter through engine exhaust ports.

If a new engine were installed and debris is present, the replacement engine may fail due to the debris being reintroduced into the combustion chambers during negative exhaust back pressure events. Technicians should be aware that when servicing an LX9 for a catastrophic engine failure, an inspection of the catalytic converters for debris (on the exhaust manifold attachment end) be performed. In addition, cases where severe engine overheat is suspected of causing engine failure, dealers should inspect each catalytic converter ceramic brick for signs of heat damage (melting or cracking of the ceramic brick). If heat damage is noted, the converter should be replaced.

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Please follow this diagnosis process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed. If these steps do not resolve the condition, please contact GM TAC for further diagnostic assistance. This diagnostic approach was developed for the vehicle with the VIN you entered and should not be automatically be used for other vehicles with similar symptoms.

(04 Chevrolet Malibu)

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