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Oxygen sensor codes p0161,p0158

15K views 9 replies 2 participants last post by  8isgreat 
#1 ·
Hi everybody
I bought my jeep "02 4.7 HO" with the CEL (check engine light) on. Previous owner told me it was because he had removed the mini cats. I installed magnaflow hi-flow cats and replaced all four O2 sensors with new OEM sensors. While doing this I found that the 2/2 sensor plug had melted on the exhaust pipe at some stage. I repaired it but the CEL keeps coming on after resetting (disconnect batt). Sometime after only driving a short distance, sometime as far as 50 km. Performance and fuel consumption is normal and is not affected by light on or off. How do I fix this? Any suggestions?
 
#2 ·
The P0161 code means that the O2 sensor heater circuit is shorted or open. The P0158 code means that the O2 sensor sensing circuit has a too high voltage. Are you sure that the repair to the connector was done properly and that it is not internally shorting the pins (due to the heat damage. Did you also follow the wiring to see if there is no other heat damage to it?
Did you remove the wires from the connector, with a change that the wrong wire is now connected to the wrong circuit?
 
#4 ·
A too high voltage code can be caused by a short between a sensor wire and the positive heater wire. Do you have a scanner which shows live data? If so, then you can monitor the respective sensor output. Since its an after cat sensor, the voltage is mostly fixed or changing very little, but should not go over the 0.9V.
This sensor is used for catalyst efficiency monitoring, so will have no or very little effect on the mpg.
 
#6 ·
You can buy a scanner with live data, or when you have a smart phone, just install the free app Torque. You will then just have to buy a dongle of e bay for USD 15 and can see live data, errase check engine light and see fault codes.
 
#7 ·
Hi everybody
I eventually received my e-bay OBD bluetooth dongle (the first one never arrived).
Sensor 2/2 showed a permanent 1 volt reading. I then took the old 1/2 sensor modified the plug to fit ( only the plastic tabs on the plugs prevent them from being installed in different locations ) and installed it in the place of the "new" 2/2 sensor and viola it works. I can not monitor the heater circuits but the voltage ranges between 0.1 and 0.8 no lights on the dash. I am a happy camper.
 
#8 ·
Is the 2-2 sensor fluctuating between 0.1 and 0.8V? That should not be normal, the after cat sensor should give a quite fixed voltage and not the same as the 1-1 or 2-1 sensors.
If it is like this, then you can expect a new code soon.
 
#10 ·
100 km later, 1/2 and 2/2 does go up and down (0.1 to 0.8) lower at idle and higher at cruising (120km/h) they do not fluctuate wildly. 1/1 and 2/1 is more active bur also lower at idle than cruising. Fuel trims long and short term stay under plus or minus 2%. Sound normal? No check engine lights even after several shut downs and restarts.
 
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