And please feel free to question any of the steps I’ve taken or if you need more info on the vehicle. Once I discard any wiring issues, I guess I have to move on to finding someone with a better scanner to see if there are any manufacturer codes set that make the computer behave this way.Īny help is appreciated. I only have a very basic DVOM, and a generic OBDII Bluetooth dongle with a couple of Android apps. Another constraint is that the PCM connectors make it very difficult to back probe specific pinks on its connectors. What I’m trying to figure out next is for tests ideas on how to verify 100% the integrity of the wiring for both sensors BEFORE I have to undo all the wiring (connectors are located in a very uncomfortable place). My suspicion is that it is a problem that only presents itself WHILE running (that is, when all the conditions to activate the downstream heating circuit are met - short circuit? damaged wiring? I am just learning about voltage drop tests, and how to do a 12V to O2 signal with licked fingers (thanks to Paul’s videos) and verify if the computer reads something. 12V on heating circuit for the downstream O2 did OK too (but, with the engine off, just the switch ON). I don’t believe that is the issue, since there is signal for a few minutes after a cold start.Ĭontinuity tests on reference, signal, and heating circuit ground for both sensors did OK. Only thing I have yet to do is verify 12V on the upstream sensor heating circuit. I have already followed almost all troubleshooting procedures related to O2 sensors circuits. No luck, it just sets a P0136 and P0141 code, and STFT goes to almost 100%. One thing I tried was to do a test drive with the downstream O2 sensor disconnected, see if that disables the “double loop mode”. (P0141)Īfter replacing both, lost signal issue was present, but no DTC codes have appeared (at least yet).
Check here: Before I replaced both sensors, I had a downstream O2 heating circuit DTC.
It seems they want to come back while the car is running, but very weak.Īccording to the manufacturer service manual, downstream O2 is used for a “double loop” mode. Following that, downstream O2 signal starts climbing up to 1V and after a couple minutes both signals are gone. Vehicle: Renault Clio III 2007, 16V 1.6L, manual gearbox.Īfter about 7-10 minutes of a cold start, upstream O2 signal goes very low and even reaches 0V. And, after a Cam belt job (which apparently went OK) and a cooling fan replacement due to motor pulling too much power, I am now stuck at an O2 signal issue. So I got into DIY automotive repair a few months ago.
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