Ford Mustang 1989-1993 Repair Guide

Catalytic Converter


All Ford Mustang's use a 3-way catalyst and some also use this in conjunction with a conventional oxidation catalyst. The conventional oxidation catalyst, containing Platinum (Pt) and Palladium (Pd), is effective for catalyzing the oxidation reactions of HC and CO. The 3-way catalyst, containing Platinum (Pt) and Rhodium (RH) or Palladium (Pd) and Rhodium (RH), is not only effective for catalyzing the oxidation reactions of HC and CO, but it also catalyzes the reduction of NOx.

The catalytic converter assembly consists of a structured shell containing a ceramic, honeycomb construction. In order to maintain the converter's exhaust oxygen content at a high level to obtain the maximum oxidation for producing the heated chemical reaction, the oxidation catalyst sometimes requires the use of a secondary air source. This is provided by the thermactor air injection system.

The catalytic converter is protected by several devices that block out the air supply from the thermactor air injection system when the engine is laboring under one or more of the following conditions:

Cold engine operation with rich choke mixture.
Abnormally high engine coolant temperatures above 225°F (107°C), which may result from a condition such as an extended, hot idle on a hot day.
Wide-open throttle.
Engine deceleration.
Extended idle operation.


Catalytic converters operate at extremely high temperatures. Do not attempt to remove the converter until it has been allowed to cool, or bodily injury may result.

  1. Raise and safely support the vehicle.
  3. Disconnect the secondary air supply tube from the fitting on the converter, if necessary.
  5. Remove the retaining clamps or mounting bolts, as necessary and remove the converter.
  7. Installation is the reverse of the removal procedure.