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2003 Honda Accord Hesitating and check engine light on

My 2003 Honda Accord with 101,000 miles started hesitating on acceleration, and a day later my check engine light came on. I went to the auto parts store to borrow one of their diagnostic computers. The code I received for the engine light was from my O2 sensor. What can cause the hesitation and the O2 sensor to read faulty? I have had several O2 sensors go out on other vehicles, but that hasn’t caused any other symptoms before. I would like it to be that simple, seeing as how easy they are to replace, but I don’t want to get my hopes up. Anyway, the car is parked now and I am taking the bus because I can’t afford to take it to a mechanic. I don’t want to waste any money by starting to replace things without having better direction. Thanks for reading.

How do you know it was for your O2 sensor? Was that the interpretation of the sales person at the car parts place? You need to post the actual code here to get valid advice. The code will be a letter and 4 numbers, the code readers used at the car parts houses generally only read the P0xxx codes.

If the gave you a printout from the cash register that suggested the O2 sensor, then the actual code should be at the top. If not, go back and have them run the code again and get the actual code and post it here.

That CEL (check engine light) is just a kid in class waving her hand trying to get you attention because she has the answer. You need to have the codes read. Some places will read them for FREE. Try Autozone or Advanced Auto Parts. Get the exact code (like P0123) not just their translation into English and post it back here.

The code is P0141 on the print out. The definition written underneath is HO2S12, heated oxygen sensor-bank 1 sensor 2.

That code is for problems relating to the O2 sensor that is in back of the catalytic converter, but the sensor may not actually be the source of the problem. Before you go to the trouble of replacing the sensor, check for an exhaust leak, as that can also trigger that code. Many chain muffler shops will check your exhaust system without charge.

A disconnected wire running to the sensor can also be the reason for that code.

After 11 years, it is certainly likely that the sensor is bad, but by checking the things that I listed, you may resolve the problem. If you do replace the sensor, I suggest that you avoid the “universal” ones, and instead buy a Denso-brand O2 sensor specifically made for an '03 Accord. A good auto parts store, like Napa, should have this for less cost than what a dealership would charge.

This link may help.

Would those problems cause the hesitation when accelerating also?

No…The downstream sensor is simply monitoring the efficiency of the CAT…

The “hesitation” you describe is probably misfire of some sort that is not profound enough to set a fault code of it’s own…But the misfire sends too much unburned fuel into the exhaust system for the converter to handle so it throws a code…But even THAT is suspect, because the code was for the sensor heater circuit, which is not related to a engine performance problem. So the hesitation and the CEL are probably two separate issues…

You can try to force the issue by doing a few full-throttle acceleration sprints which should bring the misfire problem to the attention of the ECM and perhaps a code related to the problem will be set…

Something you can do yourself, clean the throttle body and mass airflow sensor and the PCV system. Replace the air filter if it’s dirty and inspect the intake path for any debris…next comes spark plugs and valve adjustment, if applicable…

Yes, this sensor can cause hesitation and can have a big affect on fuel economy, but the code is not for the sensor itself. The sensor is operating within its parameters. The code is for the heating circuit for the sensor.

These sensors do not work when cold, they have to be heated up. The exhaust gasses will heat them up, but that can take up to 10 minutes or so, in the meantime your fuel trim is operating in open loop mode, not the most efficient. The manufacturers put electric heaters inside some of the O2 sensors in order to heat them up faster and get the engine into closed loop operation quicker.

This code can be caused by the heater element inside the O2 sensor or it could be due to a wiring problem external to the sensor. You might get by with disconnecting the sensor, spraying it out with some contact cleaner and then reconnecting it. If that works, the CEL will disappear after about three drive cycles.

Most of the time, this code is caused by the heating element inside the sensor and the sensor must be replaced. As stated above, you cannot use a universal sensor, you must get one with the correct number of wires and connection pattern. It does not need to come from the dealer though. and this is the rear sensor, the one behind the cat.

It is the FRONT oxygen sensor, the one before the converter, that controls fuel trim. It can have a big impact on mileage and engine performance. The rear sensor is there to monitor the performance of the converter and it has no control over engine performance issues…

The car is my wife’s and we just got married in July, so I’m not aware of the maintenance history. She says that she has been taking it to the dealership for all maintenance. Whenever they have told her to do something, she lets them do it. However, I don’t think they kept up with it very well considering they had never had her change her tires in six years, and the belt and battery were way passed due when I had met her. (Actually, they did finally tell her to change her tires the week after we had them replaced.) I think I’m going to check the basics such as plugs, throttle body, exc. I’ll also spray out the sensor, take it to muffler shop, or check the wiring in order of cheapest and easiest solutions. Thanks for all the advice. I post back with the results.

Caddyman, the rear sensor does affect fuel trim. It has to skew the trim slightly in order to see if the front sensor is working. The system is called a “hunting” system. The rear sensor can skew the trim too far and affect the drivability and the fuel consumption, though it usually makes the engine run a little leaner, getting it better mileage.