DTC 443: TWC Efficiency
- Perform a compression check on all cylinders. See appropriate ADJUSTMENTS article. Repair as necessary. If compression is okay, go to next step.
- Check for air leakage in intake system. Repair as necessary. If there is no air leakage in intake system, check for air leakage in exhaust system. Repair as necessary. If there is no air leakage in exhaust system, check fuel and residual pressure. Repair as necessary. If fuel and residual pressure are okay, retest using new TWC.