PhatBotti Tuning

Troubleshooting for Common ISSues


Taking longer to start the car aka You got dat weak crank bro

-  Battery is beginning to die

-  Corrosion on the MAF and/or MAF extension cable

-  Over oiled intake filter

-  Spark plugs

-  Vacuum/Boost Leak (intercooler couplers, charge pipe, leaky bov)

Huge Sustained AF Correction/Learning aka Constant +-30-40% Values

-  Vacuum/Boost Leak   (intercooler couplers, charge pipe, leaky bov) 

Your tune made my windows stop working

Go to the broken window and get it all the way up or all the way down then hold the button in that same direction for 10-15 seconds.  #magic

Tried to put map on AP got "this map does not match your vehicle"

This warning usually appears when Cobb updates the software.  IE, when trying to load a new Gen2 speed density map when a Gen1 map is installed.  Since Gen2 doesn't match Gen1, the warning appears.   Just click ok.  Once the map is on the AP, click on it and look at the info at the bottom of AP Manager and verify the AP serial number and car year both match your vehicle.  If they do, then proceed to flash the map and do the logging.  If they don’t match, then email me back and let me know there is a discrepancy.  

Why does my car feel so different in different temperatures?

-  The FA is greatly affected by temps over 90 degrees.  At this temperature timing and boost are reduced in order to help prevent knock in the hot temperatures.  The car will continue to lose power and feel sluggish as the temps go past 120, 130, etc. This is all based on the temp measured at the MAF sensor, NOT the ambient temp outside.

-  The engine bay is scorching after sitting at a stop light, so it will feel very sluggish leaving a light in hot temps but will get back to normal as the airflow cools everything off. 

-  Temp and elevation changes are accounted for in the tune and should not really cause any issues.

Misfire Troublshooting

·  Intake air leak

·  Faulty spark plug 

·  Fuel injector harness is open or shorted 

·  Fuel injector circuit poor electrical connection 

·  Ignition coil harness is open or shorted 

·  Ignition coil circuit poor electrical connection 

·  Insufficient cylinder compression 

·  Clogged or faulty fuel injector 

·  Faulty ignition coil

·  Incorrect fuel pressure 

common Check Engine Light Troubleshooting


P000A through P0024 - Intake & Exhaust Cam CELs

o  Can be caused by removing the ground strap off the j-pipe

o  Can be caused by certain oils or oil additives

o  Can be caused by low oil level

o  Subaru's Troubleshooting Order

  • Clean sensors
  • Swap sensor side to side (if CEL follows sensor, that sensor is bad)
  • Replace sensors
  • Replace ecu

P0087,0088, 0191, 0192, 0193 - Fuel Pressure CELs

These CEL's are mostly thrown when the low pressure fuel pump (LPFP) has been installed incorrectly or has popped out of place.  When this happens the fuel pump does not seal and fuel leaks back into the fuel basket which causes fuel pressure issues.  When the fuel pressure is out of range for a certain period of time it will trip one of these CELs (87/88).  

The P0087/P0088 CELs can also be thrown if you're running a higher ethanol content (e60-e70) and the HPFP in your particular car can't handle it.  If the ECU is reset and the ethanol content lowered to the e50-e60 range and the CELs do not come back, then it means your car simply can't handle the higher ethanol content and your tune will need to be adjusted to run e50-e55 instead of e60-e65.

The  0191, 0192 and 0193 CELs are for the pressure sensor itself and are usually thrown if one of its wires are cut or if it is simply not plugged in all the way.

P0171/0172 - System Too Lean/Rich

These CELs are thrown when you have a large fueling discepancy.  So if your AF Correction or AF Learning are 30-40%, then you likely have a leak somewhere and it will eventually trip one of these CELs, which one depends on if the trims are positive or negative.  The intercooler couplers and charge pipe are the most common sources of the leak.  Other common causes of these CELs can be moisture in the MAF extension cable, a leaky blow off valve or a bad low pressure fuel pump install.    

P0230 & P023F - Fuel Pump Primary Circuit

These CELs are thrown when the low pressure fuel pump has been installed incorrectly.  The fuel pump is leaking internally back into the fuel basket and starts working harder and drawing more current which can cause these CELs to be thrown.  In some cases the fuel pump fuse will blow or the wiring can also melt.  The CELs can also be thrown if the fuel pump connection on top of the basket has not been plugged in all the way.

P0101 through P0108 - MAF/MAP Sensor Circuit CELs

99% of the time these CELs are from people not plugging the sensors in all the way after cleaning the MAF and MAP sensors.

P0441 through P0459 - EVAP System Leak CELs

These CELs are thrown for leaks in the EVAP system.  Most likely causes are the gas cap not being screwed on all the way or an AOS install error.



P0606 - Internal Control Module Processor

This CEL usually trips from starting the car too fast after a flash.  Simply reset the ECU and carry on.  Usually nothing to worry about.  If it persists contact your shop/tuner for further troubleshooting.

P1492 through P1499 - EGR Related

Usually from the sensor not being plugged in all the way or possibly a wire cut to the sensor.  Contact your shop/tuner with the specific code.

P2004 through P2097 - TGV Related

 Usually from the sensor not being plugged in all the way or possibly a wire cut to the sensor.  Contact your shop/tuner with the specific code. 

General High/Low Circuit CELs

Generally these CELs mean that the sensor simply isn't plugged in all the way or a wire leading to that sensor has been cut.  Throwing multiple circuit CELs at the same time usually means that a battery post connector is loose and all the sensors are losing power or the battery is dying in general.

General Post Tune Troubleshooting

Think of your car just as it was when it came from the factory.  If the car is running fine for 6 months, then one day it starts throwing check engine lights or running funny, you would make an appointment at Subaru and have them check for a mechanical issue….you don’t take the car to Subaru and ask them to re-tune it for you.  Issues that arise over time are rarely ever tuning issues.  Tunes don’t go bad over time.  99.9% of the time it’s a mechanical issue that has become prevalent over time such as sensors or filters getting dirty.  Keep this in mind when asking me to look at logs post tune.  I do charge for troubleshooting.  I simply can’t answer emails and look over logs for thousands of people for free all day long.

Flex Fuel Troubleshooting

Cobb’s flex fuel troubleshooting guide is at the link.  If you’re getting Cobb1 or Cobb2 CEL’s it means the voltage for the ethanol sensor is going out of range. THIS IS NOT A TUNING ISSUE.  You will have to email Cobb.  Cobb will ask you for a log to show the voltage out of range.  Then they will tell you that there is possibly moisture or debris in the gas from the gas station and ask you to take the ethanol sensor out and blow it out with a compressor and reinstall it.  Then they will ask what your tuner has the delays set to, they are set at 300.  After that they will require that you capture the voltage going out of range in a log and send it to them.

The ethanol sensor is a 0.5 to 4.5 volt sensor.  Anything in that range is fine.  CELs will only come on if the voltage is below 0.25 volts or above 4.75 volts for an extended period of time.  That would mean the ethanol content is either pegged at 0% or 100%.  You can watch/log ethanol raw and Sns Volts TGV L on the AP. those are what Cobb will want to see.  So if you're getting the low voltage CEL the ethanol raw should be 0 and the voltage below 0.5 volts.  Once you capture it in a log they will likely send you a new sensor under warranty. 




  • The ecu stores the DAM, AF Learning, CEL's and knock learning so by resetting the ECU you are erasing all the troubleshooting data. 
  • If your car was knocking and the DAM had dropped or had FLKC all over and you reset the ECU, then the car is going to knock all over again until the ECU relearns the knock. 
  • If you had a leak and your ECU learned +25% fueling corrections and you reset the ECU, then your car is just going to run like crap until it relearns the corrections. 
  •  Its only a good idea to reset the ECU if you have made changes to correct your issue and fully understand what you are doing. 



  • This only applies to EJ's.  The FA's can monitor AF Sensor 1 Ratio via the AP.
  • A wideband is by far the best real time monitoring device for your Subaru. The $165 investment could save you a blown engine and $5,000. 
  • Will show you your WOT AFR's. If you were tuned at 10.8 and now your AFR's are 12.5, then you need to start troubleshooting. 
  • At idle and in closed loop a Wideband mounted in the downpipe will commonly show 15-15.2 while the ECU is targeting 14.7. This is common and merely due to the location of the sensor compared to the stock 02 sensor in the header. 
  • Since the ECU is using the stock 02 sensor for corrections/trimming to 14.7 this means we basically ignore the wideband at idle....and then at WOT we use the
    wideband and ignore the stock sensor. 




o   Should stay 1 99% of the time. May occasionally drop for a multitude of reasons. If the DAM drops just continue to drive your car normally. Don’t reset the ECU, let the knock control system do its job. 


o   -1.4’s and -2.8’s should be considered normal and very common

o   -3’s and -4’s may occur during the summer, after heat soaking at a stop light, going up a long hill, having 4-5 people in the car, AC being on… if you’re driving up a hill in the summer with 4-5 people in the car with the AC on…expect lots of knock events.

AF Correction 1 & AF Learning 1

o If they have SUSTAINED values in the 30-50% range you have a leak. Most likely the intercooler couplers, charge pipe, or bpv/ebcs lines.

o Don’t watch mins/maxs, its very easy to have high min/max values during normal driving

o For the most part watching the correction and learning on the AP can just cause confusion.  If you have a leak the car will let you know because it won't start good, it won't idle good, and overall it will drive like crap.

Intake Temp Manifold

o Watching this parameter lets you know when its best to beat on your car. As the temp in the intake manifold rises so does the likelihood of knock.