1.6 tdi p2237 fault code

[Benturner166]

Hello all

 

I had this code previously and replaced the o2 sensor with a NGK lambda sensor.

 

5k miles later the code has come back and I am unsure of what to check without a diagram. Has any one got a wiring diagram for the engine ?  Engine code is CAYB

 

Or has anyone had the same issue and know a common spot for wiring to short together/ break.

 

Or have I been unlucky and this o2 sensor is broken. The car is mapped and the exhaust would get quite toasty.

 

Thankyou 

Edited 23 January, 2023 by Benturner166

[UrbanPanzer]

You have probably cooked the new sensor, or it's just failed again.

 

P code tells you the sensor is faulty, worth checking the wiring to the sensor, if that looks good then another sensor would be first "fix".

Edited 23 January, 2023 by UrbanPanzer

[sepulchrave]

I doubt it's cooked, probes get much hotter in petrol engines, more like to be sooted up, you could try cleaning it with carb cleaner.

[UrbanPanzer]

fair point,  being mapped it's going to overfuel / smoke more so sooting could be an issue.

[Benturner166]

1 hour ago, UrbanPanzer said:

fair point,  being mapped it's going to overfuel / smoke more so sooting could be an issue.

 

2 hours ago, sepulchrave said:

I doubt it's cooked, probes get much hotter in petrol engines, more like to be sooted up, you could try cleaning it with carb cleaner.

Hi guys thanks for the suggestions. Car still has a dpf and doesn't have any sooting up issues.  The code is for the heating element inside the sensor being open/ short circuit. I will pull the sensor and check it out for carbon since it is straight after the turbo.  If I knew the pins I could do a resistance check on the sensor. Maybe a haynes manual would cover that but not sure.

[Titanium_Man]

12 hours ago, UrbanPanzer said:

You have probably cooked the new sensor, or it's just failed again.

 

P code tells you the sensor is faulty, worth checking the wiring to the sensor, if that looks good then another sensor would be first "fix".

 

Actually, the P denotes that the fault is within the power train system, and going one step further, when the code relates to the heater element specifically it usually means that the O2 sensor itself is the issue and not the wiring. 

[sepulchrave]

23 minutes ago, Titanium_Man said:

Actually, the P denotes that the fault is within the power train system, and going one step further, when the code relates to the heater element specifically it usually means that the O2 sensor itself is the issue and not the wiring. 

 

The ECU can't tell the difference between a wiring break and the heater element going open circuit.

[Titanium_Man]

1 hour ago, sepulchrave said:

 

The ECU can't tell the difference between a wiring break and the heater element going open circuit.

Of course, but experience has taught me that it is usually the heater itself at fault and not the wiring when the code specifically mentions “heater”. No mention of “heater” in the code usually means it’s something other than the O2 sensor itself.

[Benturner166]

Hello all

 

Just thought i would update. So I have checked the wiring and its okay. Checked the plug and theres no corosion. Pins are opened up so I have closed them a little bit to make better contact. Pulled the sensor and its okay, not blocked with carbon. So with that I reset the codes and I have done about 300 miles. Nothing has come back yet.