hgoodwiniii

Hi all, I am getting diagnostic code P2240 ​(Sensor Positive Current Control Circuit / Open Bank 2 Sensor 1)The description is Bank 2/ Sensor. on my 2007 CLS 550. I understand Bank 2 is the passenger side and sensor 1 is the upstream sensor; Can anyone let me know what's involved with changing this sensor? Is it pretty easy to access it? Thanks.

konigstiger

hgoodwiniii

Thanks konigstiger.

hgoodwiniii

Hi konigstiger, I hope all is well. I'm just getting around to install the new CLS550 upstream/passenger sensor. Is the view on the 2nd picture on your 12/06 post, a view from the looking from the rear of a view looking toward the front of the car? Thanks.

konigstiger

hgoodwiniii

Ok, I see. That second picture was a view from underneath the car looking from back to front. The sensor is all changed, now. Thanks for your help.

hgoodwiniii

Hi all, I am getting code P2240 again after changing the passenger side upstream sensor. I am also getting codes P0303 (Cylinder 3 misfire detected) and P0304 (Cylinder 4 misfire detected). The car runs fine most of the time but at times it shakes and runs sluggish, then runs fine again. Any ideas on this? New spark plugs were just installed back in August. Seems a bit odd to have 2 cylinders misfiring at the same time but I suppose it's possible. Any ideas what could cause these 3 codes all at the same time? Thanks.

CaliBenzDriver

if it's not the sensor itself... it's the wiring harness. Does this engine suffer from "oil in harness" caused by leaky sensors??

Go ahead and change O2 bank 1 sensor 1 as to not cause imbalance on half your cylinders. Left and right must be given a chance to stay balanced with similar age O2 sensors.

Is your engine a bit shaky & vibrating (... loose distribution timing) ?


> Simple swap test:
-- Swap both your L & R O2-Lambda to confirm DTC stays put.
-- Put in the new unit at the same time your swapping.
-- Observe your Fuel Trims before and after swap, open loop status ?

hgoodwiniii

Ok, I will check your suggestions. This is getting weirder and weirder.

I took a scan today. I was getting the P2240 code as well as codes P0303, P0304 and P0302 indicating misfires and a check engine light. The car was idling very bad with a heavy fuel order. I cleared the codes and umplugged/replugged the bank 2/sensor 1 o2 sensor. The check engine went out, the car idled well and the fuel smell was pretty much gone. I took it for about a 30 mile drive. The car ran well and had no check engine light.

As soon as pulled back home, it started running bad, the hard fuel smell came back and the check engine light reappeared. I read the codes and now P2240 (current), P2240 (pending) and P2237 (pending) indicating a problem with both passenger side o2 sensors. Also, the electric fan(s) was spinning very fast. I did some research and found a guy in a MB forum saying he had both P2240 and P2237 on his car. He had a bad thermostat code, as well. He says he changed the thermostat and his sensor codes cleared.

Is it true that a faulty thermostat could cause these issues? Thanks.

CaliBenzDriver

Personally I don't see a bad thermostat messing up both up/downstream O2 on 4Cyl. only... Every engine's different!
Save time, while swapping your thermostat do the water pump and serpentine kit.

With the way things are acting up on their own schedule randomly... I'd check for "oil in harness".

hgoodwiniii

hi everyone, I'm just getting back to working on this CLS550 problem. I've changed the passenger side upstream sensor (twice) and the driver side upstream sensor (once) since I last posted. I have checked the wiring harness around the 02 sensor plugs for oil and corrosion and those areas look fine. I put about 15 miles on the car since and I am still getting random trouble codes. Mostly, I am getting codes P0031 and P0051, now. Car runs fine at times (especially after I clear the codes), at times it gives a heavy exhaust fume smell, then at times lots of vibration (mostly while sitting a traffic light) and then at times lots of slugginess (while driving).

These codes displayed once in my 15 mile drive P0304, P0302, P0303 (all misfire codes) and the P2240.

Anyone have any other ideas on this one? Also, where exactly in the wiring harness should I be checking for oil? Thanks.

CaliBenzDriver

The code for O2 Heater control sounds like an electrical problem. We now know the new upstream O2 are not in cause.

'Oil in the harness" contamination can be checked at the ECU connector.

Diagnose the ECU Fuel Trims, fuel pressures the engine maybe starved?

How old are these spark plugs??

hgoodwiniii

Hi CaliBenzDriver. - thanks for hanging in there with me. I will check the ecu connector, fuel trim, fuel pressure and report back. The spark plugs are about 8 months old. There are not many miles on them.

CaliBenzDriver

don't replace parts... test them first when possible to confirm suspicions with evidence. It's not going to get fixed playing parts-darts

8 month plugs are good unless they're from eBay market place ...

Look at troubleshooting data as noted in previous post...
🤞

hgoodwiniii

Thanks. No the plugs are definitely not from Ebay. I believe we went with the same brand that were in the car. I will pull one to check the brand.

hgoodwiniii

Hi CaliBenzDriver, I was able to pull look at the CLS 550 today.

Here are the items you suggested I look at::

The spark plugs we used were NKG (part no plkr7a).

The fuel pressure was registering a bit over 60 PSI

Short Term fuel trim - bank 1 was 0%; Sensor 2 = 99.2%

Long term fuel trim - bank 1 was 32.8%

Short term fuel trim - bank 2 was 0%; Sensor 2 = 99.2

Long term fuel trim - bank was 22.7%

I am posting pictures of the ecu and ecu wire harness connectors. I checked and I do not see any signs of oil.

Also, I see status for Fuel system A and Fuel has a value of "OL-Fault" for both.

I appreciate your comments and help analyzing this. I can post the remaining "live data" if needed. Thanks.

CaliBenzDriver

Connectors look as clean as new, no oil there. Lucky


Great raw data dump! Out of all that what stands out is:
> the ECU strongly enriching the mixture (32; 22) like it's unable to get enough gas from injectors.

> In addition to getting wicked code about O2 heater

> In addition to getting misfire on passenger bank only

> To recap also: new plugs and new upstream O2.

.../... ​​​​(I'll need to re-read the thread to wrap in more known details): ok.

I think this odd combination of unrelated troubles sounds exactly like poor ECU grounding.

hgoodwiniii

Ok, I will check the grounds at the battery; I did have to change the battery recently. Any other specific ecu ground locations that I need to check?

konigstiger

Regarding codes you’re getting for 273.960 only coordinating MB DTCs: 0302 - The fuel injector (cylinder 1) has a short circuit to ground & 0303 - The fuel injector (cylinder 1) has an electrical fault or an open circuit, I suggest checking fuel distributor / injectors.

CaliBenzDriver

It's not BATT GND because it doesn't affect 100% circuits indiscriminately - Realise that here your issue is mainly on passenger bank1 besides strong positive LTFT on both banks.

To answer your question: the exact info about ECU branches grounding is located in WIS with your specific VIN#.

You can spend couple hours to study the schematic branches then cross-reference locations...
-Or
simply save schematic time and go for diagram of ALL GND locations on engine and chassis.
-Or
Without any specific diagram you can clean ALL GND screws you find on the engine.

✌️

hgoodwiniii

Ok, I will get back to it this weekend. Thanks for the help.

hgoodwiniii

I checked and I really saw only 2 grounds in the engine bay. One (plug type) near the rear of engine on passenger side of the manifold that looks to be coming off the fuel injector wiring. The second on the driver side seems to be coming off the driver side fuel injector wiring attached to the car body in the under the hood fuse "box" area. These seem to be ok. Anyone know of anymore?

Also, I did see a bit of oil in the rear engine intake area highlighted in the attached picture. However, it does not appear there is any harness wiring in the area.

Here is the recap:

The ECU is throwing codes

P2240 (Sensor Positive Current Control Circuit / Open Bank 2 Sensor 1) and P2237 (Sensor Positive Current Control Circuit / Open Bank 1 Sensor 1)

P0300 (Random/Multiple Cylinder misfire), P0301 (Cylinder 1 misfire), P0303 (Cylinder 3 misfire) and P0304 (Cylinder 4 misfire). P0302 showed previously instead of P0301
koningstiger, these descriptions are a bit different than what you supplied. They are what show up on my scanner. Can you let me know the source of what you supplied? Thanks.

Live data shows

Fuel trim indicates not enough fuel being supplied from injectors

Fuel A and Fuel B showing "OL Fault" in live data

Other items

New plugs (NKG- purchased from Rockauto), new MB battery and new MB Upstream 02 sensors

ECU harness/connections look clean.

Fuel pressure measures ~60PSI

Car is running rough with a heavy gas smell and lots of **** at tailpipe tips


I appreciate any thoughts on this. Could there just be a problem with the ECU? Air flow sensor? Not sure where to go from here except to take it to a repair shop? Thanks.

CaliBenzDriver

it may not seem like it but you're making progress when you eliminate what this problem is not.

I would concentrate on fixing your O2 heater circuits. Misfirings come from the lean mixture, ignore them for now.

You've replaced both upstream O2 and also found no bad ECU GND, or oil in harness.

Test the +12 feed side from SAM...
Measure voltage at fuse under load
Probe wiring for continuity at O2 connector.
Use a basic test light to see if ECU control GND is present

This O2 heater issue is symmetrical: both sides, same problem, same time

hgoodwiniii

Ok, thanks I'mCaliBenzDriver. I will do it. Good point you make on the problem elimination process. Thanks.

hgoodwiniii

Hi everyone, I got a chance to work on the CLS 550 today.

Here is the latest

I did verify that I am getting power to 3 of the 6 cavities on the female side of the driver side and passenger side upstream O2 sensor connections while grounding the test light on the engine. I also verified that the fuse related to the upstream sensors is #57. The test light lit very bright on one cavity, not as bright on another and very dim on the3rd one that had power. However, I was able to verify that there is no grounding in any of the upstream cavities. Is this normal? I'm thinking I really need to get my hand on a wiring diagram

I did verify that the ECM has a ground on it. I put my test light on the ecm body and the other side on a hot fuse and it lit up

I sent the ecm for testing and was told there were no hardware issues found with it

I did not get a chance to test +12 on the SAM or the fuse #57 under load. Needed a helper for that. .

I appreciate any thoughts. Thanks.

find out that fues #57