Check Engine Light
Thread Starter
|
New User
Joined: Dec 2002
Posts: 20
Likes: 0
Check Engine Light
Hey guys haven't had a chance to get on the forum for a while, and low and behold I'm having a problem with my 99Expy XLT with 123552 miles on it. The check engine light came on, so I had the codes read, if I remember correctly it was Po135 and Po140 not sure but I know it had something to do with the 02 sensors. SO I went ahead and change all four with the bosh ones from autozone. Had the codes cleared and the "CEL" turned off, drove down the road and started to pass a car and the damn light came on again. Checked the codes and the same codes as before came on, so I did a search and read about the pcv valve hoses so didn't get any leaks and I clamped everything down just in case. Had the codes cleared and drove off for a while, accelerated and the light came on again checked the codes and the same damn codes keep comin up, did a search and nothing can some one help?
Junior User
Joined: Dec 2005
Posts: 68
Likes: 0
Double check the PCV elbow in the back of the engine. Follow the plastic hose from the passenger side where the valve is. Remove the elbow fitting from the end of the hose/intake. There could be a small leak. You cannot inspect it unless you take it off. Look for rot in the bend of the elbow.
Also clean the MAF. That could also be the cause.
Also clean the MAF. That could also be the cause.
Junior User
Joined: Dec 2005
Posts: 68
Likes: 0
Originally Posted by 98expeditionXLT
Since I have not had to do it on my Exp. yet, I have to ask how does one clean the MAF?
Hotshot
Joined: Jan 2004
Posts: 19,768
Likes: 1,082
From: St Louis
Double check your codes. P0135 is a valid code, but there is no P0140.
P0135 is for a heater circuit for the upstream passenger sensor. P0141 is for the downstream sensor heater same side.
Need to know the EXACT codes and which engine....
The MAF has absolutely nothing to do with O2 sensor heater circuits. Same for the PCV hose.
Again, get the EXACT codes..... you've already wasted considerable time and money on blown diagnostics.
Steve
P0135 is for a heater circuit for the upstream passenger sensor. P0141 is for the downstream sensor heater same side.
Need to know the EXACT codes and which engine....
The MAF has absolutely nothing to do with O2 sensor heater circuits. Same for the PCV hose.
Again, get the EXACT codes..... you've already wasted considerable time and money on blown diagnostics.
Steve
Trending Topics
Senior User
Joined: Oct 2004
Posts: 326
Likes: 0
From: North Alabama
Originally Posted by projectSHO89
....The MAF has absolutely nothing to do with O2 sensor heater circuits.....
Steve
Steve
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
Top 10 Fords at 2026 Carlisle Ford Nationals
Joe Kucinski
3 Best / 3 Worst Parts of Modern Ford Ownership
Brett Foote
10 Amazing Upgrades That Solve Common Ford Truck Owner Headaches
Pouria Savadkouei
Every 2026 Ford Engine Explained
Brett Foote
10 Ugly Ford Trucks That We Still Kinda Love
Joe Kucinski
10 Things Every Truck Owner NEEDS (2026 Edition)
Michael S. Palmer
Rezvani's Latest Post-Apocalyptic Monster Is a Ford F-150 Raptor Underneath
Verdad Gallardo
Top 10 Most Expensive Ford Trucks Ever Sold on Bring a Trailer
Joe Kucinski
2027 Ford Super Duty Buyer's Guide (Every Model, Engine, & Package)
Brett Foote
Hotshot
Joined: Jan 2004
Posts: 19,768
Likes: 1,082
From: St Louis
Originally Posted by wavinwayne
Not so fast; If the MAF is dirty, or otherwise not working properly, it can cause the engine to run lean. The lean condition can cause O2 sensor codes to be thrown.
I specifically said "HEATER" circuit.
I did not say anything about fuel trim...
The heaters are used during cold engine warmup to reduce emissions on startup by bringing the O2 sensors online more quickly. They are turned on electrically and individually by the PCM under the control of the PCM's operating strategy and mode.
Yeah, I'm crabby today. Been working on my tax return all morning...
Steve
Last edited by projectSHO89; Apr 7, 2006 at 11:44 AM.
Senior User
Joined: Nov 2003
Posts: 467
Likes: 1
From: Where the war is...
MAF Sensor cleaning
I'm confused about how you folks (in the linked post above) recommend cleaning this sensor. One of you says just to spray the electric cleaner directly on the sensor (wire), nothing else. Another of you says to use alcohol and qtips, which seems to indicate you want us to manually touch the wire to clean it. What is the proper method/technique and cleaning fluid? What is it we are trying to remove off of this wire/sensor? Can you provide more details? Thanks!
Last edited by vze2sgxa; Apr 7, 2006 at 11:52 AM. Reason: clarify which 'folks' I was referring to in the linked post
Senior User
Joined: Oct 2004
Posts: 326
Likes: 0
From: North Alabama
Whatever you do, DO NOT TOUCH THE MAF SENSOR WIRES!!! Don't worry about removing the MAF sensor from it's housing. It's a lot of work that is unnecessary. Do this:
1. Remove the negative cable from the battery, then remove the positive cable.
2. Unlatch the air filter housing clamp; This will allow you to shift the MAF housing to the left enough so that you can see inside of it.
3. To the left of the air filter housing, look inside the MAF sensor housing; You'll see the wires inside the MAF sensor housing. Spray the MAF sensor wires real good with CRC electronic cleaner.
4. Let dry for a few minutes, then re-assemble everything & you're good to go.
1. Remove the negative cable from the battery, then remove the positive cable.
2. Unlatch the air filter housing clamp; This will allow you to shift the MAF housing to the left enough so that you can see inside of it.
3. To the left of the air filter housing, look inside the MAF sensor housing; You'll see the wires inside the MAF sensor housing. Spray the MAF sensor wires real good with CRC electronic cleaner.
4. Let dry for a few minutes, then re-assemble everything & you're good to go.
Hotshot
Joined: Jan 2004
Posts: 19,768
Likes: 1,082
From: St Louis
Geez, why ya screwing with the MAF sensor.....
There is no indication it needs attention. Plus, if you screw it up and break the wires by dinking around with it and Q-tips, you'll learn an expensive lesson...
There is no indication it needs attention. Plus, if you screw it up and break the wires by dinking around with it and Q-tips, you'll learn an expensive lesson...
Senior User
Joined: Feb 2004
Posts: 163
Likes: 0
From: Columbia, SC
Our 98 5.4 was really sucking down gas like crazy, it even sounded like an old car with a 4 barrel carb when you accelerated, well after some investigating I found the PCV rubber grommet was deteriorated, yes the one in the back, bought a new one at Ford for about $40, what a difference, big gain at the pump, sorry exxon I know 31.6 billion profit just wasn't enough last year.
Hotshot
Joined: Jan 2004
Posts: 19,768
Likes: 1,082
From: St Louis
Originally Posted by Big Craig
Our 98 5.4 was really sucking down gas like crazy, it even sounded like an old car with a 4 barrel carb when you accelerated, well after some investigating I found the PCV rubber grommet was deteriorated, yes the one in the back, bought a new one at Ford for about $40, what a difference, big gain at the pump, sorry exxon I know 31.6 billion profit just wasn't enough last year.