Stalling after starting?

Tiny
NETDALE10
  • MEMBER
  • 2004 HONDA CIVIC
  • 1.7L
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 175,000 MILES
My car will start every time but sputters and dies immediately after it srarts. Smells like sulfur sometimes. Have codes P0171 P0134, P2A00 I have replaced the Oxygen sensor.
Monday, July 7th, 2025 AT 7:19 PM

26 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,144 POSTS
Hi,

Two of the codes are specific to oxygen sensors. The one that has my attention is the P0171. That code indicates a lean fuel mixture. Have you checked to make sure there are no engine vacuum leaks? If not, start there. Here is a link that explains how to check.

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

If you cannot find one, the next thing would be to check the fuel pump pressure. It can be too low or too weak to run the vehicle. I attached the directions and manufacturer's specifications below.

Let me know if this helps or if you have questions.

Take care,

joe

See pics below.
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Monday, July 7th, 2025 AT 9:33 PM
Tiny
NETDALE10
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  • 15 POSTS
Thank you for such a quick response. I am checking for leaks right now. I do have a leaky plug on the end of the cam shaft cover. Oil is leaking there. Is it possible that this is the problem? I have to wait a few days until the new one arrives. I just find it hard to believe that this problem is caused by a leak somewhere. The car always starts. But sputters and dies as soon as the car starts. If I try to rev it up, the rpm goes up but sputters and dies.

Also measured the fuel pressure. It is a steady 45psi
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Friday, July 11th, 2025 AT 10:53 AM
Tiny
NETDALE10
  • MEMBER
  • 15 POSTS
I am confused. I don’t see any response here. Only see some other comments supposedly related to my issue.
Thank You
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Friday, July 11th, 2025 AT 11:15 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 52,740 POSTS
Sorry for the delay, the fuel pressure is good, it seems like you have a large vacuum leak. This is why the oxygen sensor cant respond and the PCM is dumping fuel into the engine.

P0171 - System Too Lean (Bank 1)
P0134 - O2 Sensor Circuit No Activity Detected (Bank 1 Sensor 1)
P2A00 - O2 Sensor Range/Performance (Bank 1 Sensor 1)

Here is what you need to do to find the leak.

https://www.youtube.com/watch?v=LRKWV4Are5c&t

The leak detector is like $62.00 on Amazon.

https://amzn.to/3InmPwo

Let us know what you find.
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Friday, July 11th, 2025 AT 11:45 AM
Tiny
NETDALE10
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  • 15 POSTS
Why is the engine is getting too much gas if the code says it’s running lean.

Also I should mention that I believe that the head gasket is bad. The car will overheat if at low speed or idling too long. Have to put about a pint of water it it every time I make a trip.
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Friday, July 11th, 2025 AT 11:54 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 52,740 POSTS
So if the long term trim says it is lean, then the short term trim will try and richen the mixture. This is why you smell the cats over working themselves. It can be a bad fuel injector as well that, is why we need to run the tests I presented to see what the problem is, there is no "one" answer to this problem, we must run some tests. If you remove the spark plugs and look at them it can tell us if a particular cylinder is causing the problem. You can upload an image of the plugs so I can see. I hope this helps.
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Saturday, July 12th, 2025 AT 9:00 AM
Tiny
NETDALE10
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  • 15 POSTS
Here are the the pictures:
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Saturday, July 12th, 2025 AT 9:38 AM
Tiny
KEN L
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Yep, now we know it is not one cylinder causing it. There is a fuel vapor line I need you to check that goes to the engine, it should not have fuel in it. Here is the location so you can check it out. Thanks for the images. Check out the images (below).
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Saturday, July 12th, 2025 AT 9:58 AM
Tiny
NETDALE10
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  • 15 POSTS
I believe that this is the line you are referring too. It looks like a return line for the fuel. It is dry inside
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Saturday, July 12th, 2025 AT 10:10 AM
Tiny
KEN L
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Low vacuum can cause this issue as well, if the exhaust system is clogged ie: clogged catalytic converter it will cause this issue. Did the engine have good power before all of this started?
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Saturday, July 12th, 2025 AT 10:20 AM
Tiny
NETDALE10
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  • 15 POSTS
Yes. Plus that was my very first check. I unbolted the exhaust manifold from the engine and stuck my leaf blower I. The tail pipe. No blockage at all. To be sure I even tried to start the car. No difference
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Saturday, July 12th, 2025 AT 10:23 AM
Tiny
NETDALE10
  • MEMBER
  • 15 POSTS
I’m wondering if the fuel injection is the problem. The car does try to accelerate when I press the gas petal. But stutters and stalls. It just seems like it isn’t getting gas into the engine. I haven’t figured out an easy way to check them. I have order a good scanner so I can monitor the signals going to the injectors without me having to put my frequency Fluke meter on the actual wires that are hard to get to.
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Saturday, July 12th, 2025 AT 10:34 AM
Tiny
KEN L
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It sounds like it can be a weak fuel pump or the camshaft timing has jumped. Here is the camshaft marks so you can check it. Check out the images (below).
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Saturday, July 12th, 2025 AT 6:28 PM
Tiny
NETDALE10
  • MEMBER
  • 15 POSTS
Thank You I’ll check it tomorrow. I checked the fuel pressure. It is a steady 45psi.
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Saturday, July 12th, 2025 AT 6:33 PM
Tiny
KEN L
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Okay, yep I would check the timing of the camshaft. Have a good Sunday!
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Sunday, July 13th, 2025 AT 11:57 AM
Tiny
NETDALE10
  • MEMBER
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It took me some time to check it. It is about maybe 1 tooth off.
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Friday, July 25th, 2025 AT 4:15 AM
Tiny
KEN L
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One tooth off is enough to cause low engine vacuum which will cause the ECM to give the engine excessive fuel. I would install a new timing belt.
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Friday, July 25th, 2025 AT 9:46 AM
Tiny
NETDALE10
  • MEMBER
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The timing is now dead on. No difference in running. But I installed a new Upstream O2 sensor and got some interesting numbers:

now that I’ve replace the O2 sensor. I think these number made further indicate a vacuum leak:

At about 1500 rpm (throttle position 17.5%:

Manifold Absolute pressure 85.4 kpa
O2 Sensor bank 1 S1 .781 lambda

It looks like we never pull much of a vacuum and the engine actually runs rich.
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Saturday, July 26th, 2025 AT 11:59 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
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Hmm, does the car have a catalytic converter on it? It may be clogged, please go over these guides to help us see what it going on.

https://www.2carpros.com/articles/why-an-automotive-engine-will-run-rich

and

https://www.2carpros.com/articles/how-to-test-a-catalytic-converter

Please go over these guides and get back to us.
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Sunday, July 27th, 2025 AT 10:47 AM
Tiny
NETDALE10
  • MEMBER
  • 15 POSTS
That was the first thing I checked. I disconnected the exhaust manifold and tried to run the car. I also blew air from a leaf blower. It is fine. I am convinced that the head gasket that I know is bad it the root cause. I am trying to test the engine compression. It is not easy to test on a Honda. I need an extension pipe to reach down to where the plug goes
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Sunday, July 27th, 2025 AT 10:53 AM

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