Quote:
Originally Posted by Clodfobble
Which symptoms was I supposed to report?
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If a first failed converter put extra strain on the second, then you reported a failure of the first converter a month plus ago. A second converter failed only recently. As I said, those are the symptoms you were supposed to report if the mechanics diagnosis was accurate. You did not report those symptoms.
You did report symptoms that, for example, report a failing oxygen sensor. It was probably first failing as much as a year ago. Could have been seen long ago by a computer attached to the diagnostic ports. But only recently got bad enough to cause an error code. Do not confuse that oxygen sensor with others on the converters - which, in hindsight, I believe you and others were doing.
Meanwhile, the mechanic's analysis (bad converters) do not explain error code P0174.
An intermittent error code implies your always existing failure is slowly getting worse. Or only gets reported when detected in consecutive engine restarts.
Furthermore, error code P0174 may not cause a check engine light. May be detected repeatedly by the engine computer. But only reported on its diagnostic port.
Some designs have a ‘diagnostic plug’ that, when attached, causes unreported error codes to appear as a flashing check engine light.
Driving conditions (and even different gas) may cause a marginal problem to be worse. Always there and detected by monitoring numbers from various sensors. Those codes can be created by a long list of possible suspects. Blaming two failed converters was way down the suspect list.
Suspect list could be shortened significantly by monitoring numbers from various sensors, as noted above. But you cannot do that without a maybe $120 computer that plugs into every car's computer (ie Car Chip). Check engine light can be cleared by that layman’s tool, or sometimes by a ‘diagnostic plug’.
A least expensive solution is to watch this problem. Wait for it to become so obvious that any mechanic can fix it the first time. However if a check engine lights repeatedly, then fix it now to avoid possible future engine damage.
I suspect a P0174 error code still exists. That error code, alone, does not trigger a check engine light. But my wild speculation is based only in experience - not in facts required from the shop manual. Speculation is best anyone here can do without further information from that plug-in computer (sold even in Sears and Wal-Mart) and from a shop manual.
Your best suggestion is in a paragraph that starts, "A least expensive solution ...". I, on the other hand, have a nasty habit of doing things on cars that also exposed Saddam's WMDs and Tokyo Electric's lies about Fukushima. Ruthlessly, finding numbers and irrefutable facts (that explains all three error codes) requires information currently not available.