Your Altima pulls away normally, but the check-engine light is on. A catalytic converter can lose its ability to clean exhaust while still letting it flow freely, so the car may feel unchanged. We diagnose converter warnings and replace failed converters at Precision Auto Care in San Leandro. We also check for engine faults that can overheat or contaminate the converter, because those faults need repair before they damage a replacement.
An Efficiency Warning Can Appear Without Power Loss
Exhaust passes through a coated structure inside the converter. Chemical reactions at that surface reduce harmful emissions. The coating can deteriorate while the passages stay open. Exhaust still gets through, but the converter isn't cleaning it well enough.
Oxygen sensors before and after the converter help the engine computer monitor its performance. An efficiency warning means the readings need investigation. A poorly running engine changes the exhaust entering the converter, and an exhaust leak can affect sensor readings too. We check those problems before deciding that the converter has failed. Replacing it without correcting an engine or exhaust fault can leave the warning unresolved.
A Restriction Can Make Acceleration Weaker
You press the accelerator to join traffic, and the Altima struggles to gain speed. If a converter's internal structure has melted or collapsed, exhaust has less space to escape. As you ask the engine for more power, it has to move more exhaust through that reduced opening. Fuel-delivery and ignition faults can cause a similar hesitation. An exhaust backpressure test measures the resistance to flow and helps locate a blockage. We check that pressure on either side of the converter to find where exhaust is being held back. The blockage may be inside the converter or elsewhere in the exhaust, which changes the part that needs repair.
A Rattle Can Start Inside Or Outside The Converter
Loose material inside a damaged converter can rattle against its metal housing. A heat shield can make a similar sound outside it. From the seat, either may sound like something vibrating beneath the floor.
A loose shield may need securing while the converter remains usable. A broken core calls for replacement, and loose pieces can also restrict exhaust flow. We locate the noise before recommending the repair.
A replacement converter also has to suit your Altima's emissions system. California requires an original-equipment converter or an approved aftermarket replacement for the specific vehicle. We match the replacement to the car's application, including its engine and emissions configuration. Physical fit in the exhaust pipe is only one part of selecting the correct converter.
A Misfire Can Overheat The Converter
A misfiring cylinder can send unburned fuel into the exhaust. When that fuel burns in the converter, the extra heat can damage the coating or melt the passages inside. If the Altima shakes hard while the check-engine light flashes, stop safely and avoid continued driving. We provide engine repair as well as converter replacement. Correcting the misfire protects the replacement from the same excessive heat.
An Internal Coolant Leak Can Damage The Coating
Coolant lost inside an engine may leave no drip on the driveway. If it reaches the exhaust, it can contaminate the converter's coating and reduce its ability to clean the gases. Deposits interfere with contact between the exhaust gases and the catalyst, even when the passages remain open. An external hose leak needs cooling-system repair, but it doesn't expose the converter to coolant in this way.
We repair engine leaks as well as damaged converters. If coolant is entering the exhaust, we address that engine leak before replacing a damaged converter. A replacement converter would otherwise be exposed to the same coolant as soon as the engine runs again.
Have The Warning Or Loss Of Power Checked
A warning light is worth checking even when your Altima still feels normal to drive. We diagnose catalytic converter problems and repair the engine faults that can damage them. Call Precision Auto Care at (510) 351-8211 for help at our San Leandro shop.
