HELP! Codes after Spark Plug Change
#1
Intermediate
Thread Starter
HELP! Codes after Spark Plug Change
I changed my spark plugs today. Thirty minutes afterwards, I get a check engine light and TRAC OFF message. The codes that I read are P0174, P0171 and P1170. What are those codes, and are they related to my spark plug change? Also, I used the OEM Denso plugs. Are they pre-gapped to the recommended value?
#2
Racer
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I changed my spark plugs today. Thirty minutes afterwards, I get a check engine light and TRAC OFF message. The codes that I read are P0174, P0171 and P1170. What are those codes, and are they related to my spark plug change? Also, I used the OEM Denso plugs. Are they pre-gapped to the recommended value?
#3
Lexus Test Driver
You probably need to either clean or replace the Mass Airflow Sensor (MAF).
you should disconnect the negative battery clamp before cleaning the MAF sensor. You would have to disconnect the battery after cleaning the MAF anyway to reset the ECU to adjust to the clean MAF sensor.
you should disconnect the negative battery clamp before cleaning the MAF sensor. You would have to disconnect the battery after cleaning the MAF anyway to reset the ECU to adjust to the clean MAF sensor.
Last edited by bclexus; 10-06-21 at 02:44 PM.
#6
Racer
iTrader: (2)
@lexo98 You were right. I forgot to put back in a tiny hose. Very embarrassed.
On a related note, one of my spark plugs looked like this:
Should I be worried about anything? The others didn't look so crusty.
On a related note, one of my spark plugs looked like this:
Should I be worried about anything? The others didn't look so crusty.
The following 2 users liked this post by lexo98:
jpajya (10-13-21),
Neophyte2b (10-08-21)
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#8
Lexus Test Driver
@lexo98 You were right. I forgot to put back in a tiny hose. Very embarrassed.
On a related note, one of my spark plugs looked like this:
Should I be worried about anything? The others didn't look so crusty.
On a related note, one of my spark plugs looked like this:
Should I be worried about anything? The others didn't look so crusty.
There is nothing wrong with your spark plugs and they didn't need replacing - they'll last 250k miles with no degradation in performance of fuel mileage. That spark plug can be easily cleaned up and it will be as good as new.
If you still have the same problem going on you'll have the same codes thrown again...and your brand new spark plug in that same cylinder will look the same as the one in your image. Your ECU was not happy with the inputs it was getting from one or more of those sensors.
#9
After looking at the base of the plug where the threads are above your fingers, is that wetness? Did you spray WD-40 in the spark plug hole before trying to remove? Or by any chance was the plug very easy to remove? Have you ever replaced your PCV (Positive Crankcase Ventilation)? Do you ever notice sluggish acceleration? Lots of questions but you got me Wondering whats going on.. 😃
#10
Lexus Champion
iTrader: (1)
@lexo98 You were right. I forgot to put back in a tiny hose. Very embarrassed.
On a related note, one of my spark plugs looked like this:
Should I be worried about anything? The others didn't look so crusty.
On a related note, one of my spark plugs looked like this:
Should I be worried about anything? The others didn't look so crusty.
#11
Lexus Test Driver
Only ~55k miles I believe. He said the other spark plugs don't look like the one he posted an image of. A bad fuel injector could be the culprit...
Last edited by bclexus; 10-07-21 at 06:17 PM.
#12
Clogged injector or wasnt tightened down all the way along with his PCV being old and clogged..but you would think they all would look similar. I say use some good fuel system cleaner (Lucas Fuel System Cleaner is what i use) along with some shell/chevron 93 or 91 octane and then give the ole girl an "Italian Tune Up!!!". The reason is; is that for most people (like myself) life gets mundane and repetitious to which the responsibility moves in and the excitment and thrill move out taking the fun and "**** it!!" Attitude with it. This in return makes us drive more responsibly by just giving the throttle enough gas to get up to speed and thats it. This causes carbon and combustion residual's to collect in places it shouldn't, one of these is the spark plug. So go drive your car like it was a rental and bang that redline through the gears....when doing this look in your rear view mirror and you will see black clouds that will make Ricky Bobby proud👍🏻. Alot of little random quirks or hiccups cars have can be solved with some full throttle punches.
The following users liked this post:
Neophyte2b (10-08-21)
#13
Lexus Test Driver
Clogged injector or wasnt tightened down all the way along with his PCV being old and clogged..but you would think they all would look similar. I say use some good fuel system cleaner (Lucas Fuel System Cleaner is what i use) along with some shell/chevron 93 or 91 octane and then give the ole girl an "Italian Tune Up!!!". The reason is; is that for most people (like myself) life gets mundane and repetitious to which the responsibility moves in and the excitment and thrill move out taking the fun and "**** it!!" Attitude with it. This in return makes us drive more responsibly by just giving the throttle enough gas to get up to speed and thats it. This causes carbon and combustion residual's to collect in places it shouldn't, one of these is the spark plug. So go drive your car like it was a rental and bang that redline through the gears....when doing this look in your rear view mirror and you will see black clouds that will make Ricky Bobby proud👍🏻. Alot of little random quirks or hiccups cars have can be solved with some full throttle punches.
#14
Lexus Champion
iTrader: (1)
A bad injector could do that too. Something did it? I can't think of any reason someone prior would go in just 1 cylinder and muck up, and/or how they could produce that? I have seen something close to that on the Lincoln LS where water would get down in one plug cylinder due to the front window rain seal run down in just one cylinder, cause the rubber boot to mess up firing the coil then give a throttle body ecu code due to a short. Had that same pinkish color with black carbon just like that plug.
Also the PCV would not just effect just one cylinder only? Would it?
Last edited by jgscott; 10-07-21 at 07:18 PM. Reason: spelling