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I have a 1999 740il that had a code 1540. I replaced the cam sensor on the drivers side and now I have a code po340. The check engine light comes on after the vehicle has been run, then turned off and restarted. I check the wiring to the cam sensor and it looks good at the sensor as well as at the ecm. I then put another new cam sensor in to make sure that it was not a bad sensor. I pulled the valve cover and inspected the sensor wheel at the cam. It is not bent or damaged. The vehicle has had a new radiator, hoses, plugs, fuel filter, as well as a crank sensor. I just checked codes again and now for the first time have a code PO1175 also. I used Just answer and had another BMW expert try to work with me but he couldn't help me. He requested that I withdraw from his services and try someone else. Can you help me? The vehicle runs great except for the check engine light.

Submitted: 241 days and 21 hours ago.

Category: BMW

Value: $40

Status: AWAITING EXPERT REPLY

1999 BMW

Posted by Kellie 241 days and 20 hours ago.

Info Request

I just want to verify a few things...

The first code, 1540, does not come up when I search. Are you sure that's the code, and if so, what is it for? Is the second code you listed, P0340, for the same sensor you replaced? And are you sure you typed P1175 correctly as well? It comes up as a fuel trim fault, I just want to make sure I'm seeing the same thing as you.

What brand camshaft sensor did you install?

241 days and 19 hours ago.

Reply

Sorry, the first code was PO 1519. I replaced the cam sensor with an aftermarket brand. Code P1175 is correct. This is the first time that I saw this code. It has not came back yet but PO 340 comes back after restart.

Posted by Kellie 241 days and 15 hours ago.

Answer

Okay, that was the answer I wanted to hear because it means you've got an easy fix. Return that aftermarket sensor and demand your money back because they never, ever, ever, ever, EVER work. You have no idea how many professional technicians I've seen run into problems with aftermarket sensors and chase their tails trying to figure out why they can't get rid of their cam sensor code. Buy an OEM BMW sensor from the dealer and try again. I bet that code will clear.

Just to be certain though, that first code, P1519 hasn't returned since you installed the new sensor?

The fuel trim code may be due to an intake leak or a bad MAF. Both are very common on this engine.

241 days and 15 hours ago.

Reply

code P1519 has not returned. I will pick up a new BMW sensor and install it a let you know in the next day or so.

241 days and 1 hours ago.

Reply

Ok, I bought a new BMW cam sensor and installed it. I cleared codes, started the car with the code reader installed and the code PO340 was there. Then I turned off the car and restarted it and the check engine light was on as well as the code PO340.

Posted by Kellie 240 days and 7 hours ago.

Info Request

I'm sorry if this seems like a silly question, but are you sure you're replacing the right sensor? If so, inspect the wiring and the connector. I find it odd that P0340 only appeared after installing a new cam sensor. If you reinstall the old sensor, does the code go away?

240 days and 6 hours ago.

Reply

I replaced the sensor on the passengers side , below the maf. I have inspected the wiring all the way to the ecm and it appears good. I have not reinstalled the old sensor. I don't even know if I still have the old one.

Edited by XXXX XXXXX X XXXX on 3/26/2009 at 9:14 PM

Posted by Kellie 239 days and 19 hours ago.

Answer

Try swapping the sensors from bank to bank and let me know your result.

233 days and 19 hours ago.

Reply

Sorry I have been out of town. I swapped the cam sensors and now have a code P1340, misfire. The cam code is not there at this time. I only drove the car for a few miles. The engine is not missing and runs smooth. I will drive it 20 + miles tonight.

Accepted Answer

No problem. Did the misfire code set the check engine light? Definitely drive it and let me know if the faults return.

Accepts:
Expert:	Kellie
Pos. Feedback:	100.0 %
Answered:	4/2/2009

BMW Technician

Level 1 BMW Tech, ASE Master Tech

233 days and 15 hours ago.

Reply

Ok, I now have codes p1340, p135, p1175. No cam sensor code and the vehicle runs very good. I do have a small leak from the rear valve cover on the passengers side that I will take care of this weekend. Any ideas from here? I know that the code 135 is the O2 bank 1 sensor 1. Does that mean I need an O2 sensor? What is the fuel trim adpt additive?? for code 1175?

Posted by Kellie 233 days and 15 hours ago.

Answer

Alright! Sounds like you've got one problem taken care of. I'm glad to hear it!

Fuel trim additive means that the engine has to compensate to keep its air/fuel ratio at the proper level. What that fault code isn't telling me is which direction it's compensating. I need to know if it's adding fuel or subtracting fuel. Nine times out of ten on this engine, that fault appears because of a small unmetered air leak. Usually they're from the intake manifold seals. It's very common for the rubber seals to deteriorate. Spray it down with brake cleaner while it's running and see if the idle changes. If the leak is bad enough, you'll hear a noticeable difference. Occasionally, I see vehicles throw unusual fuel trim faults when the MAF fails, but air leaks are more common.

229 days and 18 hours ago.

Reply

I checked for leaks as you requested but none appeared. I used brake fluid, and even tried water but there was no change in how the car ran. I again have a code P1340, engine misfire upon start. It does not appear to be missing at all and runs good at this time. I am lost as to what to check for. Should I pull the manifold and replace the gsk's anyway?

Posted by Kellie 229 days and 17 hours ago.

Answer

Sometimes the leak isn't bad enough for the brake cleaner trick to work, and certain brands of brake cleaner work better than others. Before you spend hours resealing the intake manifold, I'd take the car to a dealer or BMW indy shop and ask them to check the fuel adaptations. You may have a bad MAF.

221 days and 4 hours ago.

Reply

I replaced the maf and the code 1340 came back as soon as the key is cycled.

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1999 BMW

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Sorry, the first code was PO 1519. I replaced the cam sensor with an aftermarket brand. Code P1175 is correct. This is the first time that I saw this code. It has not came back yet but PO 340 comes back after restart.

Answer

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code P1519 has not returned. I will pick up a new BMW sensor and install it a let you know in the next day or so.

Reply

Ok, I bought a new BMW cam sensor and installed it. I cleared codes, started the car with the code reader installed and the code PO340 was there. Then I turned off the car and restarted it and the check engine light was on as well as the code PO340.

Info Request

I'm sorry if this seems like a silly question, but are you sure you're replacing the right sensor? If so, inspect the wiring and the connector. I find it odd that P0340 only appeared after installing a new cam sensor. If you reinstall the old sensor, does the code go away?

Reply

I replaced the sensor on the passengers side , below the maf. I have inspected the wiring all the way to the ecm and it appears good. I have not reinstalled the old sensor. I don't even know if I still have the old one.Edited by XXXX XXXXX X XXXX on 3/26/2009 at 9:14 PM

Answer

Try swapping the sensors from bank to bank and let me know your result.

Reply

Sorry I have been out of town. I swapped the cam sensors and now have a code P1340, misfire. The cam code is not there at this time. I only drove the car for a few miles. The engine is not missing and runs smooth. I will drive it 20 + miles tonight.

Accepted Answer

No problem. Did the misfire code set the check engine light? Definitely drive it and let me know if the faults return.

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I replaced the maf and the code 1340 came back as soon as the key is cycled.

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I replaced the sensor on the passengers side , below the maf. I have inspected the wiring all the way to the ecm and it appears good. I have not reinstalled the old sensor. I don't even know if I still have the old one.

Edited by XXXX XXXXX X XXXX on 3/26/2009 at 9:14 PM