3 Common OBDII Error Codes, What They Mean, And Their Solutions


When check engine lights first appeared on cars, the solution was simple — take the car into a shop. Now that cars are equipped with on-board diagnostic systems (OBD, OBDII), the idea is that by plugging a reader into the OBD or OBDII port, the problem can be diagnosed and fixed immediately.

It's not that simple. Codes simply refer to one of the sensors within the vehicle, many of which can be tripped by various problems. Here's a look at three of the more common codes, what they mean, and how you can fix them.

The Code: P0442

The Problem

One of the more common codes on a vehicle is P0442. If this shows up, it means there's a vapor leak somewhere within the system. These leaks can occur in holes "as small as .04 inches [in] diameter." This code can show up if there's something as simple as a gas cap loose, or as complex as valve or o-ring defects.

The Fix

The fix can be as simple as replacing the gas cap and driving around for a while until the code goes off, or as complex as bringing your car to the shop for a vapor leak test. Shops can usually detect a leak by using a scanning tool or a smoke test.

The Code: P0133, P0135, P0141

The Problem

One of these codes means there's a problem with one of your O2 sensors. Each code corresponds with a specific bank and sensor number. Your car will probably operate normally, although you might notice a slight dip in your fuel efficiency.

The Fix

The go-to option here is to replace the O2 sensor in the designated location, but it's not always the correct choice. These readings can also occur from damaged wires leading to the sensors and leaks. If exhaust is leaking into the system, the change in the percentage of oxygen causes the sensor to signal a problem, even if the sensor is working just fine.

The Code: P0300, P0301, P0302, P0303, P0304 P0305

The Problem

If you took a look at those codes and realized there were six of them and also realized that many cars have six cylinders, you probably realized these codes related to cylinder misfires before this sentence ended.

The Fix

Good luck figuring it out on your own. Misfires are caused by a host of issues. Some of these include:

  • Vacuum leaks
  • Loose or cracked hoses
  • Intake manifold gasket leaks
  • Vacuum brake booster leaks
  • Lean fuel mixtures
  • Dirty fuel injectors
  • Low cylinder pressure
  • Poor fuel mixture, or gas with too high or too low of a alcohol or water content

Unless you're a mechanic, or know your way around an engine block well enough to diagnose a problem, it's best just to find an engine repair shop, like Leading Edge Automotive, for cylinder problems.


22 December 2014

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