My 2005 Dodge Dokota 4.7L V8 152,000 miles has an intermitent check engine light (CEL) code P0420 (‘catalylst efficiency’) that turns itself off.
- 151,000 CEL on, code P0420, checked, cleared at dealer.
- 151,948 CEL on, code P0420, checked, cleared at dealer (Cat Conv est $800).
- 152,200 CEL on, code P0420, checked, cleared at local auto parts store.
- 152,597 CEL on. No checks.
- 152,815 CEL turned off on its own
- 152,849 CEL on. No checks.
- 153,137 CEL turned off on its own.
Twice in this time CEL has came on soon after a fill up from near empty.
Engine runs fine, 18-19 mpg highway.
Have seen numerous on-line reports of other possible causes:
a) base engine problems (coolant or oil) – coolant temp sensor
b) Air inleakage – air systems or manifold
c) Lazy front O2 sensor
d) fuel pumps
e) timing or misfire
f) what else? - (gas cap, other…)
Anyone have ideas on what to check first or categories to eliminate?