99 Honda Civic - Code P0141
#1
99 Honda Civic - Code P0141
I am in California. I have a 1999 Honda Civic DX 4 cylinder. A couple of days before smogging the car my check engine light pops on. Checked the code and it was P0141, downstream O2 sensor. We replaced the downstream sensor and ran the car. Thirty minutes later the same code P0141 comes back. I cleared the code and drove the car for a day and the light did not come on. Took the car for a smog test and it passed with flying colors. Total HC's at both idle and higher RPM were between 9 and 13. A day later the check engine light came on again and now the code is P0420 for bad cat. The car has 340,000 miles. The cat was replaced before and has somewhere around 120,000K miles. I cleared the codes again to see what the computer spits out next time.
Any suggestions are greatly appreciated.
Any suggestions are greatly appreciated.
#3
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Re: 99 Honda Civic - Code P0141
If it passed the sniffer with flying colors and the sensor is new I would inspect your wiring to that sensor. The wiring could be damaged and intermittently giving improper readings.
#4
Re: 99 Honda Civic - Code P0141
Thanks. Any chance it could be the ECU? Also, how would you go about checking or fixing the wiring?
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Re: 99 Honda Civic - Code P0141
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#9
Re: 99 Honda Civic - Code P0141
I would think if the cat is bad the readings from the smog test would not have been so clean
#10
Re: 99 Honda Civic - Code P0141
I will when I get home tonight. The max HC allowed for both idle and upper RPM is 100. The average was I think between 14 and 20. I think my car measured between 9 and 13
#12
#15
Re: 99 Honda Civic - Code P0141
The engine seems to running somewhat lean. Unexpectedly for CA, NOx emissions are not shown on the sheet. I suspect your cat is dead, but this is not evident because NOx measurements were not reported.
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