I have a 04 hyundai elantra it has a code p-2551 o2 bank 1 sensor 1 negative current cricuit/open it did this last yr i got it fixed same code has it went bad that fast or do i need to look for a bad wire or something plz help.

Probably replaced a good sensor. This codes could be from a bad sensor, a vacuum leak, or an exhaust leak before the sensor.

The codes that i have pulled out relates to Oxygen sensor and Catalyst converter faults.
P0420: Catalytic converter system,Bank 1,efficiency
below threshold.
P2251: Heated Oxygen Sensor (H02S)1, Bank 1, negative current control open circuit.
But not necessary the faults. You need to run the scope to see wht patterns u get on the oxygen sensor, and on the obd scanner you may be able to pick up oxygen sensor coming on and going off or rich or lean mixture and the mvolts of the sensor. Also check if the wires are not broken on the sensor. Sometimes a clogged O2 sensor can cause these problems.

It has two sensors. Bank 1 Sensor 1 is inside the engine bay under the metal heat shield on the front of the engine. Check out NTK sensors online. The one you need will be a 4 wire sensor. The NTK part number is 24588.

P2251 L.O2 reference circuit(-) open-Sensor 1. This code is showing a problem on the reference voltage of the upper O2 sensor. It might be sensor or the wiring. P0304 Cyl.number 4 Misfire detected. This code is showing 4th.cylinder is or has been missing. Second code might be set by first code.O2 sensor problem needs to be corrected first.

Your transmission is slipping which can cause a huge amount of damage both to the car and your wallet. Take it in for service as soon as you can.

P2626 O2 Sensor Pumping Current Trim Circuit/Open (Bank 1 Sensor 1)

I'll sure this has to do with a faulty O2 sensor. This sensor is usually located around the header of your car, or down more on your exhaust.

Try disconnecting your battery for 30 mins, hook it back up, and start your car again. This will erase the error. See if it comes in again.

Hope this help (remember rated this post).

Hi, for the P0140 see http://www.obd-codes.com/p0140. For the P2251 see http://www.elantraxd.com/forums/showthread.php?20258-P2251-O2-sensor

Hi Garcha,

Both codes relate to O2 Sensor # 2

Code P0139: O2 Sensor Circuit Slow Response - Bank 1, Sensor 2
Code P0140: O2 Sensor Circuit No Activity Detected - Bank 1, Sensor 2

A faulty O2 sensor will mean incorrect signals will be sent to the EFI computer, causing erratic engine running.


Cheers,


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P1166 O2 Sensor - controller adaption diagnosis malfunction (bank 1).

Trouble area:

* P1166 is case for HO2S (Bank 1, Sensor 1) Signal line open
* Fuel system (Fuel tank/Pressure regulator/Fuel pump/PSV) failure
* Poor connection to fuel line hose/sealing/cut
* Sealing between purge valve and fuel tank
* Air leakage in exhaust system
* Ignition system (ignition coil, spark plug, cable) failure
* Surge tank and intake port failure

it is the O2 sensor in the manifold that went bad. it is an easy fix but i wouid recommend taking in to somwere other than the dealer to save you money. this is small problem that will only effect your gas milage a little