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A month ago, after driving for 2 hours, my car suddenly started jerking on the highway. By the time I pull over, the car died and everything turned off.

I was able to start the car again and exit the highway even though it was jerking at low speed. I turned off the car for 10 minutes and it wasn't as bad after that. I managed to drive home which 2 hours further.

The following check engine light was on

P0341 - Camshaft Position Sensor Circuit Range/Performance

but the mechanic couldn't find anything because it was not happening anymore. They cleared the code and it hasn't come back.

Although, 2 days after a new code appeared

P0420: Catalyst System Efficiency Below Threshold Bank 1

For this new code, the oxygen sensors were tested and they were fine so they suspect that the car needs a new catalytic converter.

After that, I was good for a month without any problem, but this week it started jerking again. It's not as bad as before, the car hasn't died on me yet but it's weird because it's intermittent. I drive about 10 hours every weekend and it would happen midway for about 15 minutes and then stop.

I added stp and gumout fuel injector cleaner and use supreme gas but it didn't make any difference.

Could it be the spark plugs?

There's no check engine light for missfire.

What should I check next?

EDIT

The Jerking is back and forth as in front to back and does not change based on the speed. The intensity varies based on the day, not the rpm or the speed. Most days it's really subtle or not present and other days it's shakes so hard that I have to stop and restart the car. I haven't tried to put my car to neutral while this happens. I will try next time and post an update.

  • Awesome. If the problem goes away when you put it in neutral, that means it's definitely a transmission issue (either way, it doesn't hurt to check your transmission fluid like Thread says below). If it doesn't, it's probably not. Does the intensity vary based on how much gas you're giving it? Also, do you smell any gas after it's been happening for a while? If you smell gas, that means it's probably not a transmission problem, and is an electrical problem (cylinders not firing). – Cullub Jun 10 at 15:06
  • @Cullub It hasn't happened in the past 2 days, so it's hard to tell but I don't remember smelling gas. Not sure about the intensity either, I will have to test next time it happens. – Marc Jun 11 at 12:33
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This could be either a drive problem, or an engine problem.

One easy check for whether it's a transmission problem is to put it in neutral, and see if the problem continues. If it does (stays relatively the same), then it's not a transmission problem (your transmission is disengaged). If it's a transmission problem, you'd start by checking fluid, and then trying to narrow it down to the transmission or the differential (probably one of those two).

I'm leaning toward it being a drivetrain problem, since that seems to match the symptoms, although the codes don't quite match. Since it doesn't change with how fast the car is moving, that limits it to the transmission.

If it's not a transmission problem, then it's an engine problem. The engine needs three things to run: fuel, air, and spark. So you'll have to start by narrowing it down to one of Gas, Airflow, or Electrical.

  • If you smell gas while the problem is happening, that probably means that the problem has to do with gas not being burnt when it should. So it's getting gas, but not burning it. Electrical or Airflow.
  • If it's a gas problem, it will probably be related to how much gas you're giving it. You mentioned that it doesn't have to do with whether you're accelerating, so my guess is that it's not a gas problem.
  • Electrical: Your engine codes seem to suggest that it might be an electrical issue of some sort. The first code might've just come on because the engine was running really rough, and the second one would tell me that the car isn't burning all the gas it's getting. You'd want to check spark first, then move to the more complicated parts such as your O2 sensor(s), MAF/MAP sensor, knock sensor, etc.
  • Airflow: If it were airflow, restarting the car wouldn't help.
  • Thank you! this is really good information. From your answer, it sounds like it could either be a transmission or electrical problem and it's going to be expensive to fix lol. I will try to reproduce the problem tonight and put it on neutral. – Marc Jun 10 at 17:50
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    My car is at the garage, they think it could be related to the o2 sensors. I will update soon – Marc Jun 25 at 18:15
  • They changed the 2 o2 sensors and the car runs better but I don't think the problem is fixed. Also the check engine light is still on. – Marc Aug 1 at 11:25
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Supreme gas is overkill. I would consider another cleaner like Seafoam who makes a fuel additive and top cleaner sprayed into the intake. Search youtube for info on that. They even make crankcase cleaners.

In an 07, when was the last time you changed the transmission fluid? If there is a large fleck of metal floating around your transmission that would wreak havoc if the fluid hasn’t ever been changed. If you have a dipstick, Red is okay, black fluid means change immediately. Otherwise make sure the engine oil is changed sooner than every 5000 miles.

  • I used stp and gumout for the injector cleaner. Is it similar to Seafoam? I bought the car last year so I don't know if it was changed or not but I took the car for a checkup and they said that the fluids were good. I will look into that. Thank you – Marc Jun 10 at 0:20
  • @Marc - STP and Gumout are weak compared to Seafoam & BG44K. – Pᴀᴜʟsᴛᴇʀ2 Jun 10 at 1:49

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