[paultri]

I have a 2004 Jeep Grand cherokee limited with the I6 motor and I have code p0051. I have changed the oxygen sensor twice and still get the error. I have checked the fuses and no fuse was blown. I even went as far as replacing the computer and after driving for about 2 miles the check engine light comes back on!

I do not know what else to try here ....any suggestions on what else could be causing this code?

Any help is greatly appreciated.

Thank you in advance

Paul

[QuadraTokn]

P0051

02 Sensor Heater Control Circuit Low (Bank 2 Sensor 1)

Shorted condition detected in the oxygen sensor heater element control feedback sense circuit.

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Sounds like a short in the wiring rather than a faulty sensor

[rm2001wj]

Part of the problem is that you have four O2 sensors. Your code refers to the 2/1 sensor. Which of the four sensors did you actually change?????

Bank 1 Sensor 1 (Sensor 1/1) is on the pipe between the exhaust manifold and the small cat closest to the radiator. It's an upstream sensor.

Bank 1 Sensor 2 (Sensor 1/2) is on the pipe after the small cat closest to the radiator. It's a downstream sensor.

Bank 2 Sensor 1 (Sensor 2/1) is on the pipe between the exhaust manifold and the other small cat closest to the firewall. It's an upstream sensor.

Bank 2 Sensor 2 (Sensor 2/2) is on the pipe after the other small cat closest to the firewall. It's a downstream sensor.

Here's a link to a diagram. http://www.wjjeeps.com/oxygen_40.jpg

[avpro91]

I also am having this same problem right now. I replaced the sensor (the correct one) and the MIL came right back on.

Did you ever find what was causing you problem? Thanks

[sweeneyuk]

I have a 2002 overland 4.7HO thats running very rough esp at idle.

I got codes 51, 152 & 301.

Replaced the o2 sensor pre cat bank 2 & then rechecked the codes.

now have 51, 152, 301 & 155 !

Please can someone shed some light on this issue?

If its a wiring fault how do i check it & fix it?

any help appreciated.

[rm2001wj]

The 51, 152, and 155 all refer to bank 2 sensor 1. Is it possible that the wrong O2 sensor was replaced? First, bank 2 is the right side of the engine if you are sitting in the cabin facing forward. In the US, a 2002 4.7 HO would have three (3) cats, a minicat in each pipe that comes off the bank 1 and bank 2 exhaust manifolds. Each minicat has a sensor in front and another in back. The pipes from each minicat merge to a single pipe going to the third cat. Is your UK model like that? The bank 2 sensor 1 would be in front of the minicat on the right side.

Was the replacement O2 sensor obtained from a Jeep dealer with a connector that plugged into the vehicle wiring harness, or was it a more or less universal type that needed to be wired up to a connector that then plugged into the wiring harness?

That 301 often indicates a bad spark plug in the cylinder #1 which is the one closest to the radiator in the left bank. It could mean something else is causing a misfire, but replacing a spark plug is a pretty easy test.

[Brandle]

code 301this could be a plug or plug wire issue.

[sweeneyuk]

I had the vehicle serviced in last 3 months & they changed the plugs, within a week i read up on the wjjeeps that they used the wrong plugs & quickly replaced them myself with correct plugs.

The fault stayed all the way through from the original plugs to these the 3rd set in as many months.

I bought the o2 sensor in the US, a genuine mopar part that plugged straight in. Part number 56041941AA.

I've swapped the coil packs & codes still the same.

Believe the injectors to be fine.

The codes are still pointing to the o2 sensor bank 2 sensor 1 but maybe the fault is before the sensor.

Not sure what to do next?

[CSRChicago]

Did you ever find a solution? I am fighting the same issue.