Just replaced the battery. Was able to register it properly it seems. Driving around today hoping the rough/fluctuating idle would calm down, (it did), I got yet another check engine light. Drove home and pulled the codes "P0171 System too Lean (Bank 1)", and "P0174 System too lean (Bank 2)". I may not have been successful in keeping the fuel rail connections completely clean when I had it off. But it's been a while now that I've been driving it around. Filled last tank at the nearby Valero station, but strangely there is no Top Tier signage around the station.

Anyone have an idea on how to proceed?

(Thank you in advance!)

 

At ~46457 mi I got another check engine light (DME) with only P0171. About 30 miles before, with gas at just above half tank, I filled 7 gallons 100 octane and then topped off with 91 at a 76 station in Pasadena.

Hmm, should I just continue driving to see if that one will just end up stopping also? Crossing fingers this one disappears also. Maybe I'll wait another 100 miles to feel comfortable it's actually just a fluke.

 

Okay, I’m stumped. Started car this morning and after a few minutes voltage displayed is 12.3. I disconnect the battery terminals and use a battery tool to clean up, (which I should have done when I was rushing to replace the battery in the first place, but was in a hurry to go to a funeral). I started her and no change, it is now holding steady at 12.3 V, after a little rise above and then quickly drop back to 12.3 V. I put a 75/20/6 A battery charger/jump starter to the under hood jump points. I set it to 20 A boost, no change on voltage, 12.3. I crank it up to 75 A knowing it may only last a short period, then run back to the display, no change, 12.3 V. After a while of letting it idle (time taken to post this), sitting with 20A boost mode, it is now reading 12.4 V.

My first suspect is alternator and then after this series of tests I suspect the voltmeter also. What do I replace?

Please any thoughts? Thanks!

 

check it using a handheld multi-meter

 

Thank you!

Confirmed it is doing 12.4 V via jump points under hood and battery lugs in trunk.

I do have the car on an automatic battery charger to the jump points under the hood. I removed it for testing what voltage range it settles to, 12.4 V as mentioned.

I haven't seen this behavior before. I guess I could take it to AutoZone and see if they could put a tester on it. Their alternator is five hundred something while FCP has two, one $880 and the other $900.

 

Decided to drive around, just to cruise. Maybe a total of 30 minutes, with one stop at the local Pavilions as I was passing by. Drove just fine, I guess making sure the terminal connections are nice and oxidation free helped. I did notice when I restarted after about 30 minutes inside the store that it ran rough until the voltage went back up past 12 V. Otherwise completely normal. Hmm...

 

whats the multi meter read when the car is running?

 

When it was stationary the multimeter readings matched the display, so I stopped using the multimeter and just watched the display while driving around. They matched within + or - 0.1 V.

 

Decided to wean the car off the battery charger. Drove short distances today, and the old smooth nice running car is back! Definitely consider cleaning up the battery connections of any oxidation build up with a battery tool.

 

Yesterday I started the car to drive around. After completing a few trips I got another check engine light.

When I got the chance I pulled the codes:

P1024 Fuel high pressure too high after engine off
P0171 System too lean (Bank 1)
P0174 System too lean (Bank 2)

I cleared them and then doing some online Google searching my initial suspect is the high pressure fuel pump.

Car had a scheduled AC recall appointment this morning so when the SA asked if there was any issues I showed him the codes. (I took a picture of the screen). They are still diagnosing and will keep the car until tomorrow.

 

Whenever you see a lean mixture code suspect a vacuum leak somewhere. The best and perhaps the only certain way to find a vacuum leak is a "smoke test."

How old is your battery? Advise changing batteries at four years or less, no matter what the mileage.

 

Thank you!

I hope the $253 fee for diagnostics comes up with something definitive.

​​​​​​I was told this morning that the codes are coming up as soft codes but not causing a check engine light.

Waiting for them to get back to me.

 

They gave me a quote of $542, but I wasn't clear what it was until another SA called today. They did a throttle body adaptation reset and seems to have cleared the issue.

They noted the horns have failed and front parking sensors intermittent. I passed on the $1k plus repair as my wife was already unhappy with the $542.

Should be done this afternoon, then I'll return the Macan loaner...

 

Horns and parking sensors you can do at the same time when you remove the bumper. Easy job.
do the air filters whilst you are in there.

oh, and 12v whilst the car is running is way too low.

 

Thank you again for your advice!

Regarding the battery it doesn't seem like there's anything wrong with the charging system. The times it goes down to 12.4 or 12.5 V are only after charging the battery to full with a battery charger connected to the jump points under the hood. If I don't do that it will run in the 13 to 14.5 V range which I observed prior seems normal. We are in "Stay at Home" orders and don't drive much because of this. I only noticed this happening right after charging then starting the car. It will rise up a tiny bit and then drop down to 12 V range I guess until the battery state of charge is where it's set to keep it. It doesn't go higher than 14.5 V, and it doesn't drop voltage if I slow to a stop. (Display remains at 14 V when I slow and stop as an example).

Ordered the horns from eEuroparts and will see if they are new or old type when they come in...

I took a peek at the front parking sensors a little bit yesterday. I'm afraid I don't have a clue on what to do regarding them. They are intermittently warning. Definitely not as sensitive as the '19 Macan they gave us as a loaner. Anyone have any advice on how to figure out what's wrong with them?

Thanks!