wali

Hi everyone, I have Honda Civic 2005. The check engine light comes couple of weeks ago. Mechanic tested it and told that O2 sensor is not working, therefore, need a replacement. O2 sensor was replaced but engine light comes again. This time mechanic said that first we replace alternator and chances are 50-50 and then if it not works we will replace computer and all in all it will cost 1000$. I don't know much about cars. Someone please guide me what should I do?

xRiCeBoYx

iTrader: (22)

Post up the codes your car is throwing. We really can't tell you anything otherwise

ezone

Um, wow.
Run away before you lose a leg.

Don't feel bad, apparently your mechanic doesn't either.
Your mechanic is broken.
Replace the mechanic.

wali

Thank you very much for your replies xRiCeBoYx and ezone. Car is throwing P0171.

mcnoople

p0171 is a fuel trim lean code. Nowhere does it say to replace the O2 sensor for this code without a whole lot of diagnosis first. Potential causes of p0171

Poor fuel quality (high alcohol content E20, E85) very common
Low fuel pressure (not common)
a cracked exhaust manifold can cause odd fuel trim behavior as well

Why your grease monkey thinks he needs to replace the alternator to fix a fuel trim code is a big question.

ezone

Got freeze frame data to go with this code?

USCGBM

Next question, which o2 sensor did he replace? Upstream, downstream or both? Since he wants to take you for a ride with the alternator he could have very well not replaced the correct o2 sensor. The upstream is more expensive but very easy to do yourself. The downstream is a bit more of a pain, but not too terrible to do yourself. But agreed, a lean code could mean SO MUCH MORE than just the 02 sensors.

wali

Thank you mcnoople.

@ezone: I don't have freeze frame data with the code.

@USCGBM: Upstream sensor was replaced earlier. One option is to replace the downstream sensor as well. But I don't want to do hit and trail. The mechanic diagnosis the problem and found the error between the alternator and computer causing this code.

Now going to another mechanic means that I have to pay diagnostic fee once again.

ezone

If he gets it right it will be a hell of a lot better than needlessly throwing an alternator and computer at the car.

wali

Thank you everyone for their concern. Today I went to another mechanic. He spent almost 3 hours in-front of me to diagnose the problem. The error code is P0134. When he reset the code and start the car the O2 sensor shows activity and after few minutes it turned off and engine light came back. He suggested me to use a Honda genuine O2/AF sensor and if still engine light issue not resolved then its a computer problem and better to go to dealership.

After doing a lot of research on internet I think the problem is the O2 sensor (a cheaper one 40$) replaced by previous mechanic. Honda needs a good quality O2/AF sensor. Should I go ahead to change the sensor for Honda dealership?

ezone

It cannot be correct at that price.

You can obtain the OEM sensor through other sources than the dealer but you have to know what you need first.

Got your engine code?


http://densoautoparts.com/find-my-pa...icle-selection
Visit the DENSO website and look up the A/F sensor number

then you should know what to search for purchase

wait...here
=================================================

Trim: L4 (1.7L)
Eng: D17A6
234-9005 (1)
D17A6 Engine|DENSO is the O.E. Manufacturer / Air Fuel Ratio Sensor
Position:Upstream

Label:OE Style


=================================================




Trim: L4 (1.7L)
Eng: D17A1
234-9005 (1)
D17A1 Engine|DENSO is the O.E. Manufacturer / Air Fuel Ratio Sensor
Position:Upstream

Label:OE Style










================================================== ==

Trim: L4 (1.7L)
Eng: D17A2
234-9017 (1)
Installation GuideLA990009-1407.1

D17A2 Engine|DENSO is the O.E. Manufacturer / Air Fuel Ratio Sensor
Position:Upstream

Label:OE Style

wali

Thank you very much ezone for your help. I was just looking at Denso website and realized that I need the engine code to find the exact part. Will find the engine code tomorrow and order the correct sensor. I hope this will work for me.

wali

Hi every one,
Today I replaced the O2 sensor with an original one from Honda and it seems that car is running perfectly without engine light. The O2 sensor previously used by the mechanic was a simple O2 sensor, however, Honda civic 2005 needs an AF sensor. Thank you for everyone helping here and other posts of civic forum which helped me to identify the root cause.

wali

Hi Everyone once again,
My car is now throwing P0139 code. I think now its rear sensor. Can someone please help me to find the part number from denso and NGK for this? Secondly, how much it will cost to change the sensor.

Thank you.

ezone

http://densoautoparts.com/find-my-part/vehicle-selection

http://www.ngksparkplugs.com/part_fi...t.asp?mode=nml

wali

Thanks a lot for quick response. I tried this one but shows many options, i.e., pre-cat and post-cat. I am not sure which one is the correct part no.

ezone

P0139 O2 Sensor Circuit Slow Response Bank 1 Sensor 2.

Sensor 2 = Rear sensor = secondary = "post-cat" (even if it is stuck in the middle of the cat on some of the cars)

HTH

wali

Thanks a lot ezone.