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I stumped. Idles and runs ruff. Codes P0300 P0135. New Cat Last year. Help



scottydoggs said:
Technical Description

Oxygen O2 Sensor Heater Circuit Malfunction (Bank 1, Sensor 1)
What does that mean?

This code refers to the front oxygen sensor on Bank 1. The heated circuit in the oxygen sensor decreases time needed to enter closed loop. As the O2 heater reaches operating temperature, the oxygen sensor responds by switching according to oxygen content of the exhaust surrounding it. The ECM tracks how long it takes for the oxygen sensor to begin switching. It the ECM determines (based on coolant temp) that too much time elapsed before the oxygen sensor began operating properly, it will set P0135.
Symptoms

You will likely notice poor fueleconomy the illumination of the MIL.
Causes

A code P0135 may mean that one or more of the following has happened:

  • O2 Heater element resistance is high
  • Internal short or open in the heater element
  • O2 heater circuit wiring high resistance
  • open or short to ground in the wiring harness
Possible Solutions


  • Repair short or open or high resistance in wiring harness or harness connectors
  • Replace oxygen sensor (cannot repair open or short that occurs internally to sensor)

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Technical Description

Random/Multiple Cylinder Misfire Detected
What does that mean?

Basically this means that the the car's computer has detected that not all of the engine's cylinders are firing properly.
A P0300 diagnostic code indicates a random or multiple misfire. If the last digit is a number other than zero, it corresponds to the cylinder number that is misfiring. A P0302 code, for example, would tell you cylinder number two is misfiring. Unfortunately, a P0300 doesn't tell you specifically which cylinder(s) is/are mis-firing, nor why.
Symptoms

Symptoms may include:
  • the engine may be harder to start
  • the engine may stumble / stumble, and/or hesitate
  • other symptoms may also be present
Causes

A code P0300 may mean that one or more of the following has happened:

  • Faulty spark plugs or wires
  • Faulty coil (pack)
  • Faulty oxygen sensor(s)
  • Faulty fuel injector(s)
  • Burned exhaust valve
  • Faulty catalytic converter(s)
  • Stuck/blocked EGR valve / passages
  • Faulty camshaft position sensor
  • Defective computer
Possible Solutions

If there are no symptoms, the simplest thing to do is to reset the code and see if it comes back.
If there are symptoms such as the engine is stumbling or hesitating, check all wiring and connectors that lead to the cylinders (i.e. spark plugs). Depending on how long the ignition components have been in the car, it may be a good idea to replace them as part of your regular maintenance schedule. I would suggest spark plugs, spark plug wires, distributor cap, and rotor (if applicable). Otherwise, check the coils (a.k.a. coil packs). In some cases, the catalytic converter has gone bad. If you smell rotten eggs in the exhaust, your cat converter needs to be replaced. I've also heard in other cases the problems were faulty fuel injectors.
Random misfires that jump around from one cylinder to another (read: P030x codes) also will set a P0300 code. The underlying cause is often a lean fuel condition, which may be due to a vacuum leak in the intake manifold or unmetered air getting past the airflow sensor, or an EGR valve that is stuck open.
Click to expand...

siwittschulte said:
You don't think running that low on fuel had anything to do with it? An 02 sensor is 60 dollars.
Click to expand...

Fairly sure you either missed this post that I quoted from ScottyDoggs or you ignored it. Either way, I'd suggest you read it again and pay attention to where it says, the O2 will cause the symptoms you have and the random misfire code as well.

When you get codes and don't at least research them, read what others post (who have read them) etc and keep asking about other things at the other end of the car that are typically unrelated, the end result is going to cost you more money. Your choice... it's not our money. We are a few guys trying to help you out. Posting for advice and then not taking or reading it... silly.
 


Welp not the 02 sensor. Was probably bad but not what is causing my issue no more 02 code still random misfire code. The guy at auto zone told me to look at the cam sensor.
 
I changed the plugs and air filter 3 months ago. I've had the car a little over 2 years. The wires were replaced before I bought it I think they look clean and not original. If it was a coil pack would the code come back with a specific cylinder. I was reading the Cam Sensor would cause it to die at times and possibly do funky things with the tach, so I don't think that is it. Wouldn't the cam sensor throw a diff code too? I was trying to find a thread on checking fuel pressure
 
cam sensor would toss a code for it, the crank sensor is the one that wont report sometimes. but the the crank sensor makes the car just stall while driving down the road when it feels like, and it will re start only of it feels like it at the moment or not lol.

change the plug wires, that way at least you know when they were changed last. make sure the plug wires are not touching the o2 sensor or the wires to the sensor as well.

good chance you pulled one or 2 of the plug wires apart when you changed the plugs.

and what plugs did you put in the engine?

and just so you know, you can reset the pcm, aka clear the codes (turn off the cel light) by un hooking the battery for 30 minutes, and re connecting it. if you have a problem still it will come back on in a short while.
 




Bosch did a write up that I've seen before. It went into how their plugs are not intended and dont' last long in a waste spark ignition system. Which is what our cars have.

Swap out the plugs and likely you'll notice it running much better immediately.
 
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