CEL MAF code and a P1115

[CJ_Boxster]

I know the P1115 code is "Oxygen Sensor Heating 1 After Catalytic Converter - Above Upper Limit"

But whats that mean, does that mean my O2 is going bad or does that mean my a/f is too lean cause of some other issue like a possible bad MAF or vacum leak?

Anyone else experience these 2 codes at the same time?

About 5 minutes before the CEl turned on, i was in 3rd gear 2700rpm and i slammed my foot on the gas to see how responsive the car is and once it reached about 5300rpm's it felt like i had let go of the gas pedel, then pressed it again... kinda scary, then 5 minutes later the CEL came on. And ever since then, the car has run alittle rough... misfires alittle during idle, acceleration isnt very responsive.

[Loren]

P1115 Oxygen Sensor Heating 1 Ahead of Catalytic Converter - Below Lower Limit

Your pre-cat O2 sensor is heated at startup so it can immediately start reading emissions and adjust have the DME adjust the mixture.

Your fault indicates that this pre-heating is failing to happen. Either their is a poor connection at that heater element, the heater circuit is open, the heater circuit is shorted. If you have an ohm meter you can check the sensor by:

1. Removing connector of 02 sensor ahead of catalytic converter.

2. Connect ohmmeter on pin side to pins 1 and 2.

Display: 1.8 - 2.5 ohms at 20°C.

3. Connect ohmmeter on pin side to pin 1 and 02 housing.

Display: infinite ohms

If the ohm readings are correct then look for bad or broken connectors on the sensor electrical connector.

If the ohm readings are bad and if your car has over 50-60,000 miles then the heater is likely bad and the sensor will need to be replaced.

[CJ_Boxster]

P1115 Oxygen Sensor Heating 1 Ahead of Catalytic Converter - Below Lower Limit

Your pre-cat O2 sensor is heated at startup so it can immediately start reading emissions and adjust have the DME adjust the mixture.

Your fault indicates that this pre-heating is failing to happen. Either their is a poor connection at that heater element, the heater circuit is open, the heater circuit is shorted. If you have an ohm meter you can check the sensor by:

1. Removing connector of 02 sensor ahead of catalytic converter.

2. Connect ohmmeter on pin side to pins 1 and 2.

Display: 1.8 - 2.5 ohms at 20°C.

3. Connect ohmmeter on pin side to pin 1 and 02 housing.

Display: infinite ohms

If the ohm readings are correct then look for bad or broken connectors on the sensor electrical connector.

If the ohm readings are bad and if your car has over 50-60,000 miles then the heater is likely bad and the sensor will need to be replaced.

Thanks Loren, Lets say i had to replace the sensor cause the reading were not right, would that mean i would have to replace all the sensors to avoid the CEL appearing and saying the others are bad cause theres a fresh new one installed?

[Loren]

Just replace the bad one.

The others will tell you when they die too.

[CJ_Boxster]

Just replace the bad one.

The others will tell you when they die too.

I hope that is the case, I remember reading other members threads on how after they replaced the 1 sensor, they received CEL's for the other sensors... Ill first check them with my Ohm meter on the weekend or sooner, depends on how upset i get with the cel and performance drop.

[CJ_Boxster]

Loren Thanks for your help, I replaced the o2 Sensor yesterday and all alot of the missing HP came back and im already noticing that my mileage is increasing, I drove the car atleast 20 miles and spirited too and the fuel gauge needle moved about a millimeter. Literally, the needle was touching the higher edge of the 1/4 mark on the gauge after the install of the new O2 sensor and after the spirited driving i did afterwards and the drive to work this morning... It now touching the lower edge of the 1/4 mark.

BTW, i have 104k miles on my boxster and when i replaced the 1 bad o2 sensor, i did not get the cel for the other 3 o2 sensors like some forum members experienced.