Citroen C2 O2 sensor?

[OneRandomBX]

Hey everyone, I've got a quick question about my 2005 C2 1.4i

I've been getting an intermittent Check engine light, I used a cheapo Chinese scanner to read the codes and I got P0134.
I also looked at the engine live data and sensor 1 was showing a steady 0.450.
I checked the resistance of the heating element and it's within spec.
Is the next logical step just replacing the sensor because it's most likely faulty? And in the case that the problem persists then I'll have to check the wiring.

Happy New Years!

[mickthemaverick]

I'd check the wiring and connectors before buying the sensor if I were you

[ozvtr]

The "upstream" O2 sensor (bank 1 sensor 1) should oscillate Between (about) 0.2 and 0.8 of a volt about once a second. Once the engine warms up and the engine ECU goes in to closed loop.
The "downstream" O2 sensor (bank 1 sensor 2) should remain at about 0.5 of a volt but will oscillate a little bit.

If the sensor 1 volts remain steady at 0.45V, the sensor or wiring are faulty. I have seen a few sensor heater circuits go faulty but the sensor will still work without the heater. I have yet to see the actual sensor go faulty. So I would check the wiring first.
The upstream and down stream sensors are interchangeable. However the length of the sensor wires are different. But the good news is the downstream sensor has the longer wiring. The electrical connector colour coding is different but the connectors are interchangeable. So you could remove the "post cat" sensor and put it up in the exhaust manifold. That will tell you if it's the sensor or wiring.

But disconnect and reconnect the sensor electrical connector first. There may be a bit of corrosion on the contacts?

The OEM O2 sensor is by NTK. The part number is printed on the metal housing. It's cheaper to find one on Ebay than buy one from Citroen.

Now, while I don't recommend the "cheap-knock-off" Chinese versions of the O2 sensors, I have replaced a number of genuine ones with the Chinese ones and they seem to work fine.

[OneRandomBX]

Yeah, I guess I should check the wiring first...

Thanks for all the info, my main problem is my lack of tools. The scanner and multimeter I used were both borrowed and I don't have access to them anymore.
My understanding is that I could check the wiring by testing for continuity between the O2 sensor port and ECU plug? Please correct me if I'm wrong.
But I can't find the ECU pinout online...

I've found replacement ones online, made by Bosch and Febi Bilstein, costing around 45-50 EUR. I believe those are good quality.

Edit:
Just had a look under the hood, found the part number (0ZA341-PG5), and checked the connector (not corroded at all)
The S1 and S2 ports are right next to each other, could I just plug in the sensors in opposite ports and if the error appears on S2 that rules out the wiring?
I have the option of Febi Bilstein (50 EUR) and NTY (25 EUR), is NTY any good?

[ozvtr]

The sensor 1 wiring goes from pin4 of the sensor to pinA3 of the grey 32 pin connector on the engine ECU. And from pin3 of the sensor to pinB3 of the grey 32 pin connector on the engine ECU.
The sensor 2 wiring goes from pin4 of the sensor to pinE3 of the grey 32 pin connector on the engine ECU. And from pin3 of the sensor to pinD3 of the grey 32 pin connector on the engine ECU.

If you look at the engine loom and follow it from the top of the engine around to the ECU in the battery box, and you don't see any damage to the loom, then there isn't likely to be damage to the wiring. Typical fault is corrosion at either electrical connectors. If you cant find corrosion on the connectors then it's unlikely to be a wiring problem.

Another thing you can try is putting a multi meter on Volts and measure between pins 3 and 4 of sensor 1. Dead cold it should read 0V. If you start the engine, it should change to a value somewhere between 0.2 and 0.8V. Could be positive or negative, but it should change! If it remains at 0V the sensor is dead.

Yes, if you swap the connectors and the problem "moves" you know the fault is in the sensor. If it stays, it's in the the wiring...or the ECU!

The "OZA" part number is the OEM unit (NTK). Well, if the Chinese copies are OK, I cant see anything else being worse.

[Gregca]

Citroen C2 1.4 HDI (2009) - Is it possible that my car does not have an O2 sensor fitted? I have replaced the exhaust system except for the Cat and did not come across a sensor. I have also taken a good look from the manifold onwards to make sure I did not miss anything but still come up blank. The reason I ask is that the other day my wife was driving the car when it suddenly came up with a warning (She thinks it mentioned O2 sensor) it hen went into 'limp home' mode. She stopped the car telephoned me for help. I was about to set off when she then called to say it had cleared the fault and was running fine again. This was 2 days ago since this incident no problems. I am wondering if it could be the MAF sensor that is starting to fail. I know where this is and it can also be checked relatively easily. My main puzzlement is why is there no O2 sensor to be found....? does anyone else have a 1.4 HDI without said sensor fitted or where should it be located?

[PaulC5]

You need to plug it in to a code reader to see what is going on. Assuming the engine management light came on when it went in to limp mode there, will be a fault code stored and freeze frame data which should help decide on the fault. Sensors can be expensive so do not replace anything until you have read the code. Trying to guess can prove very expensive replacing things that are ok by hoping to get it right before spending too much.

[ozvtr]

Citroen C2 1.4 HDI (2009) - Is it possible that my car does not have an O2 sensor fitted? I have replaced the exhaust system except for the Cat and did not come across a sensor. I have also taken a good look from the manifold onwards to make sure I did not miss anything but still come up blank. The reason I ask is that the other day my wife was driving the car when it suddenly came up with a warning (She thinks it mentioned O2 sensor) it hen went into 'limp home' mode. She stopped the car telephoned me for help. I was about to set off when she then called to say it had cleared the fault and was running fine again. This was 2 days ago since this incident no problems. I am wondering if it could be the MAF sensor that is starting to fail. I know where this is and it can also be checked relatively easily. My main puzzlement is why is there no O2 sensor to be found....? does anyone else have a 1.4 HDI without said sensor fitted or where should it be located?

All bets are off when you talk about DIEsel engines!!!! YES, some do not run oxy sensors. Sorry, there are WAY too many variations on a theme when it comes to diesel engines. Saying you have a 1.4 HDI means absolutely nothing. The engine type is printed on the engine block, typically on the exhaust side. The engine type can also be found in the 6th, 7th and 8th characters of your VIN.
If the engine does not have oxy sensors my guess would be, it's a DV4TED4 (8HY) engine...but that's just a guess.