Engine Error Code 4239

[mdltn]

I have a 2015 Z3 and I’m new to this forum. Over the weekend I got this error code. Does anyone know what it means?



Sent from my iPhone using Tapatalk

[boatwakes]

From the Indmar manual:


SPN 4239, FMI 1 - Adaptive-Learn Bank 2 Low (Gasoline)
• Heated or Universal Exhaust Gas Oxygen Sensor (Bank 2-Sensor 1/Bank 1-Before Catalyst)
• Check Condition- Engine Running
• Fault Condition- Bank 2 adaptive fuel multiplier lower than defined in diagnostic calibration
• Corrective Action(s)- Illuminate MIL and/or sound audible warning or illuminate secondary
warning lamp, disable adaptive learn fueling correction for key-cycle, and possibly disable
closed-loop fueling correction during active fault .
• Emissions related fault
The HEGO/HO2S sensor is a switching-type sensor around stoichiometry that measures the oxygen content present in the exhaust to determine if the fuel flow to the engine is correct. A UEGO sensor measures the exhaust content across a wide-range of air-fuel ratios with a linear output proportional to lambda/equivalence ratio/air-fuel ratio. In either case, if there is a deviation between the expected reading and the actual reading, fuel flow is precisely adjusted for each bank using the Closed Loop multiplier and then “learned” with the Adaptive multiplier. The multipliers only update when the system is in either “CL Active” or “CL + Adapt” control modes. The purpose of the Adaptive Learn fuel multiplier is to adjust fuel flow due to variations in fuel composition, engine wear, engine-to- engine build variances, and component degradation.
This fault sets if the Adaptive multiplier exceeds the low limit of normal operation indicating that the engine is operating rich (excess fuel) and requires less fuel than allowed by corrections. Often high negative fueling corrections are a function of one or more of the following conditions: 1) high fuel supply pressure to the fuel injection system, 2) a non-responsive HEGO/UEGO sensor, and/or 3) an injector that is stuck open. This fault should be configured to disable adaptive learn for the remainder of the key-cycle to avoid improperly learning the adaptive learn table and may be configured to disable closed loop.
Indmar Products 2008 All Rights Reserved 67
Draft Rev. A-Jan. 2008
PK/BK
SPN 4239, FMI 1 - Adaptive-Learn Bank 2 Low (Gasoline)

Diagnostic Aids
NOTE: If any other DTCs are present, diagnose those first.
Oxygen Sensor Wire - Sensor may be mispositioned contacting the exhaust. Check for short to ground between harness and sensor and on sensor harness
Injectors - System will be rich if an injector driver or driver circuit fails shorted-to- ground. The system will also be rich if an injector fails in an open.
Fuel Pressure - System will be rich if fuel pressure is too high. Check fuel pressure in the fuel rail during key-on, engine off and during normal operating conditions.
System Grounding - ECM and engine must be grounded to the battery with very little resistance allowing for proper current flow. Faulty grounds can cause current supply issues resulting in many undesired problems.
If all tests are OK, replace the HO2S sensor with a known good part and retest.

[boatwakes]

Basically means you'll need a new O2 sensor if all else is good.

[UNSTUCK]

That's one of the better O2 sensor theory of operations that I have read. Most of the time it is the sensor that has failed, but like was said, be sure to check the other areas as well.

[mdltn]

Do you happen to know if bank 2 is on the starboard or port side?


Sent from my iPhone using Tapatalk

[boatwakes]

I do not know but would GUESS its on the even side bank, the bank of 2,4,6,8. I have the same boat but it's in storage and can't look at it until this weekend. I would suggest grabbing a new O2 sensor, the O2 sensor socket and replace the starboard (or port) first and then do the opposite until the code clears.

[mdltn]

I’ll do that. Thanks for the help.


Sent from my iPhone using Tapatalk