Toyota 17105-20010 Left Exhaust Manifold Sub-Assembly

Regarding catalytic converters, it's worth noting that due to a mandated extended warranty covering emissions-related components, it's advisable to consult a dealer service department before replacing the converter at your own cost. The catalytic converter, an emission control device in the exhaust system, reduces pollutants. There are two types: the oxidation catalyst, which reduces hydrocarbon (HC) and carbon monoxide (CO) levels by adding oxygen to the exhaust stream to produce water vapor (H2O) and carbon dioxide (CO2), and the reduction catalyst, which lowers oxides of nitrogen (NOx) levels by removing oxygen to produce nitrogen (N) and oxygen. The two types are combined into a three-way catalyst. Proper oxygen levels are vital for its operation, as it captures and stores oxygen most efficiently when converting exhaust gases mixed at the ideal air/fuel ratio of 14.7:1. Lean or rich air/fuel ratios can impact its function. The PCM monitors the catalyst's oxygen content via upstream and downstream oxygen sensors. If it's not working, the downstream sensor indicates elevated oxygen, prompting a Diagnostic Trouble Code (DTC) and the Malfunction Indicator Light (MIL) activation. Checking the converter requires specialized equipment, but you can check for restricted converters using a vacuum gauge to diagnose the effect of a blocked exhaust on intake vacuum. If damage is found, replacement is necessary. Upstream catalytic converters are integral to the exhaust manifold. Replacement procedures vary by model year and engine type. Always ensure the catalytic converter has cooled before servicing.

Apply penetrating oil to the bolts retaining the exhaust pipe to the manifold. After the bolts have soaked, remove them and lower the front exhaust pipe, being careful not to damage the oxygen sensors.

Run the engine and check for exhaust leaks.