Error P0134, lean at idle, no power at drive

Hello,
I've a Jimny 1.3 16V VVT (2009) and the problem with error P0134 - O2 sensor circuit no activity detected.
Each time the engine is idling it goes to lean condition, upstream O2 sensor gives voltage slightly above zero volts. The short time fuel trims goes high to about 20. 
At first I checked the valve clearance - it is set as in the workshop manual. The cylinder compression is also in the proper range.
Than I changed the: spark plugs, hi-voltage cables, coils, injectors, MAF sensor and MAP sensor. No difference.
I double check the vacuum - solenoid valve, PVC valve. Also I checked the intake leaks, I can't find any visible signs...
Next I checked the exhaust system, changed the old sealing between exhaust pipes, checked the flow. No difference.
Finally I bought new O2 sensor (Denso DOX-0113) and still no difference!
If I accelerate to 2000RPM the sensor react to 0.9V, than oscillate few times 0.1-0.9V and goes low with STFT going back to 10..15.
During normal car drive I can feel lack of power so the engine is probably running lean.

What may cause such an issue? I'm in the totally in the end of the ideas. Below the screenshots from Torque.

P0134 is the up-stream O2 sensor, I am a little unsure which one you changed, but if it was the upstream then it could be a wiring fault.

Looking at your graphs, if it isn't the sensor that is faulty, then it is the wiring, most likely the heater circuit on the O2 sensor as you said it goes up to 0.9V under acceleration and then shows the normal oscillation (lots of hot exhaust gases going through warming up the sensor), but drops back down to low voltage at idle when it cools down.

O2 sensors have an inbuilt heater element as they need to be very hot to work correctly.

Fuel (rich/lean) is set as follows:
- The MAF says how much air is entering the engine
- The ECU adds fuel at a ration of 14.7 air to 1 fuel
- The upstream O2 sensor then fine tunes the ratio
- The fine tuning is seen as a fuel trim, both short term and a long term average.

When idling the upstream O2 sensor ocillates from rich to lean, several times per second, but tools like Torque will only show it less frequently as the ECU can't send the data fast enough.

The downstream O2 sensor doesn't change the fuel/air ratio, it is just there to monitor the effectiveness of the CAT. If the downstream sensor changes as rapidly as the upstream sensor the CAT is faulty. A steady line on the downstream sensor indicates the CAT is working correctly.

Your upstream O2 sensor is very low most of the time, this indicates a lean mixture and pushes the fuel trim up to the maximum. If it is a faulty sensor, your car will be running very rich and will be fouling the plugs, all this fuel and fouling of the plugs would give poor performance.

Thank You for the answer. I changed the upstream O2 sensor.The O2 downstream sensor looks to work great since if the upstream oscillates (when driving) the downstream stays steady.

If it is a faulty sensor, your car will be running very rich and will be fouling the plugs, all this fuel and fouling of the plugs would give poor performance.

I'm quite curious why downstream sensor is also lean rather than reach if the STFT is high?Nevertheless I'll try to check the voltage directly on the wires by the oscilloscope. Some more screenshots in the attachment.

Looking at your latest graphs these look normal, O2 sensor 1 oscillating over 80% of the range and downstream fairly steady.

I wouldn't worry about the downstream sensor been a small bit on the low side, as far as I know it isn't used for anything other than checking that the CAT is working correctly.

I have Torque on my 2011, I can't remember what the downstream O2 sensor reads, it might be a bit more than yours, but not a lot, I could try to get a picture tomorrow?

I checked the O2 sensor you fitted, Denso DOX-0113, this comes up as a universal part, it is a sensor with a wiring kit for you to splice on to the original cable and connector. I recently fitted these to my other car and was then warned that the crimp up connectors are not very reliable, so I changed all four to the correct part with the connector already fitted.

It could be that you either have the wrong O2 sensor or have a bad connection on the 'made up sensor'.

I will try to find the original sensor part number for your car.

Robin

According to a cross reference a Denso DOX-0354 is the correct part number for pre-CAT and DOX-0350 for post CAT.

Search on Google, they are around £55 in the UK. A word of warning, a number of sellers with UK sounding names are owned by a company called AutoDoc, they ship out parts from Germany and take 7 - 10 days to arrive, despite what they say on the website.

There are a few UK suppliers, they might be a couple of quid more, but you can get them next day.

Hi,

I have attached a couple of photos from my 2011 Jimny showing the O2 sensors.

The first two were taken on the open road doing just less than 60mph and were taken about 3 miles from home so the engine wasn't really up to temperature.
 
 

The last was taken at idle after a 10 mile journey. 
 
The post CAT sensor was a little lower when it first started to idle and you can see it slowly rising, but it doesn't get back up to the same level as seen when pulling 3,000rpm.

A lowish reading post CAT at idle is very likely normal, it just says that some of the O2 is been used to reduce or oxidise the harmfull gases.  The output of the CAT should be Carbon Dioxide.

Robin