A P0420 code doesn't always mean a bad catalytic converter — it can mean a failing oxygen sensor, an exhaust leak, or oil contamination. For Alderwood Manor drivers near the Alderwood Mall corridor and I-405, Tom's B&M Auto diagnoses the root cause before recommending converter replacement. We also install CARB-compliant converters that pass Washington State emissions — not cheap universals that set the same codes 6 months later.
P0420/P0430 diagnosis: oxygen sensor waveform comparison, exhaust leak check upstream of converter, oil consumption assessment, and coolant contamination check. We confirm the converter is actually failing before recommending replacement.
CARB-compliant direct-fit converter installed. Direct-fit units maintain correct oxygen sensor bung positioning — critical for accurate post-converter O2 readings. Anti-theft shield installation available for high-theft vehicles.
Post-installation oxygen sensor waveform check to confirm converter is functioning. Drive cycle completed to set readiness monitors before emissions test. Converter replacement backed by 24-month/24,000-mile warranty.
Noticing rotten egg smell, rattling under the car, failed emissions or reduced power from your exhaust? Alderwood Manor drivers trust Tom's B&M Auto — your local mechanic and auto shop minutes from Alderwood Manor on Hwy 99. Our ASE-certified technicians handle catalytic converter diagnosis, replacement and emissions repair for all makes, domestic and foreign. We offer honest car repair with upfront pricing, no hidden fees, and a free multi-point inspection with every visit. Same-day catalytic converter diagnosis available — same-day service available for most vehicles. Proudly serving Alderwood Manor, Snohomish County and surrounding areas since 1985.
A catalytic converter doesn't fail from normal use — it fails because something upstream destroyed it. Burning oil coats the substrate. A coolant leak from a head gasket poisons it. Unburned fuel from a misfire melts it. Replacing the converter without fixing the underlying cause destroys the new unit within months. We find and fix the root cause first.
Catalytic converter theft is a significant problem in the Lynnwood area — Prius, Tacoma, and Honda Element converters are the most targeted. We can install anti-theft converter shields for these vehicles. Call us for pricing on your specific model.
We diagnose why the converter failed before recommending replacement.
Washington State emissions-compliant converters. Not cheap universals.
For Prius, Tacoma, Honda Element — high-theft targets in the Lynnwood area.
Catalytic converter service includes P0420/P0430 diagnosis (O2 sensor waveform comparison, exhaust leak check, oil consumption assessment), root cause repair, CARB-compliant direct-fit converter installation, and post-installation drive cycle.
From Tom's B&M Auto - serving Alderwood Manor and the greater Seattle metro.
Tom's B&M Auto · 17820 Hwy 99, Suite E, Lynnwood · Serving greater Seattle
Also serving: Edmonds, Mountlake Terrace, Shoreline, Mukilteo, Kenmore, Alderwood Manor