Tripped check engine light, no noticeable gains
597318
No noticeable difference in gas mileage, OR power.

Also tripped my check engine light. My Lincoln is now displaying "The On-board Diagnostics System has detected a problem with the engine, transmission or an emission-related component or system."

As instructed. Car was left with the negative terminal unplugged for more than 24 hours during installation.
874397
This mechanical gauge had lots of "stiction". After showing 7-10lbs of boost, it would sometimes stay at that reading even while the engine idled. A tap on the gauge would bring it back to zero. Sometimes while under low boost (2-5psi) the gauge would stay at 0 until I tapped it again. I removed it from the vehicle once it's shortcomings became apparent. I tested it off the vehicle and it had the same symptoms.
3653191
I haven't really noticed much difference in gas mileage, performance or sound. I have had it on my truck for a month. I will update later if I notice any difference.
572845
Caused my 2010 Toyota Tundra to throw a check engine light.  Put the Fram back in and everything back to normal.
2838002
I had to update this to a one star review.  This unit slowly started failing, but could not pinpoint it as such with my voltmeter on the bench.  The issue started as an intermittent slight misfire at idle, between 800-1000 rpm about a month after install, without the engine light coming on.  My car has OBD1, so not super easy to read real time data through the computer, saw nothing strange. Issues ended up getting slowly worse at idle and some while driving and the engine light came on.  This was 4 days ago, so I went through my computer and was getting a random misfire code, so inspected the distributor cap, rotor, and plug wires that were installed new at the same time as this coil in late January (about 2 months ago).  Went so far as to spend $40 at the dealership for the factory plugs, no change.  Next morning the car ran fine, assumed it was a loose connection from the coil to the distributor cap.

Today as I'm driving the car starts and drives decently, as the issue was intermittent and haven't returned in the last 4 days,  then instantly it began misfiring badly on the highway at 65mph and loses power and I begin to decelerate.  I limped it to the shoulder, misfiring so badly it just shuts down on its own, pop the hood, and smell burning electrical and see the coil pack smoking. Saved the old coil in the trunk in a box, popped it back in and it starts!  Ended up grabbing a used OEM coil off a junkyard car that didn't have cracks, purrs like a kitten again!

BUYER BEWARE, this is a cheap unit that may or may not work!
4762416
I was constantly having the CEL (Check Engine Light) lit when driving my Mazda Rx8, I used a OBDII scanner and found that code P0171 System too lean Bank 1 and P0101 (similar in nature to their generic error code descriptions).  I attempted to clean the old Denso Maf sensor, but I found little dirt/oil on the sensor and the air filter was clean during me trying to trouble shoot the code from blog recommendations.  I opted to replace this with the Walker Product instead of the Denso, which I fear may come back to bite me later on as some blog posts mention that the Denso has a far lower failure rate compared to other aftermarket MAFs.'  In the meantime I reset the ECM by deleting the codes using my OBDII scanner, and so far there has been no further codes thrown yet - although that could possibly change as I see multiple posts about the above codes being caused by other parts of the evap/fuel monitoring systems.
3016353
Only rpm stepper motor worked and one light out of the 5 i put on works.. Dont buy if you worry about engine overheating
278795
The Check Engine light has been on my 2005 Suburban and a code reader indicated two problems, with the gas cap possibly being responsible for one of the faults.  I installed this cap, disconnected the battery, re-connected the battery, and the Check Engine light was still on.  Whether it cleared one of the codes, I don't know yet, but I'm still satisfied that I have a little extra insurance that my fuel will remain in the tank and without any unwanted "additives".
4125393
I used 2 bottles of this and my check engine light is still on. I have the 420 code and I thought this would work. I even upgraded my gas from 87 to 93 with both bottles. I don't know if there is another reason than the catylic converter needs to be clean or replaced with this code.
1588119
Cleared the upstream o2 sensor light on my low-mileage 2005 Corolla XRS. Getting the old sensor out was awful - stripped the threads and had to have an exhaust shop re-thread, but light immediately went out and has been off since.
3259704
while i was satisfied with the purchase,my check engine light returned after 5 days. My next purchase will be from the dealer. I may have just gotten a defective part.
2398514
Weekend car, only drove a couple hundred miles after installing the sensor... then put away for the winter.  Pulled car out of storage in the spring and the low coolant light stays on dim and flickers, despite full coolant level.
1670053
I used the entire 90 but the check engine light came on. So I stuffed the tube with steel wool and now light is off. Used0-0 wool because that's what I already had.
274061
I got a light in form of an engine on my 2005 Civic.  This instrument found a fault but instead of giving me code for a bad oxygen sensor it gave me "not applicable."
970544
This simple magnetic sensor when faulty can cause havoc in your jeep.  2001 XJ Cherokee, 150K miles.
Preliminary systoms, Engine would not re-start after driving and parking Jeep. Battery checked, post connectors cleaned.  Problem seemed to have been corrected.  Engine died at hwy speeds, engine re-started a few seconds later.
Jeep died again while driving, did not restart until a few minutes later, drove a few miles, died again.  Jeep had to be towed in, mechanic's preliminary diagnosis, faulty electric gasoline pump.....

It seemed to me that the gasoline pump was not the issue.  Here are the clues that pointed to the sensor;
1)Problem occurred when engine was warm and had been driven for 5 miles or more.
2)When engine died at hwy speeds, gauges went dead; tach, speed, and fuel. The engine appeared to be fuel starved and I could hear it turning (tach indicating zero RMPs did not make sense, I believe this is clue number one....sensor drives the tach per say).
3)Battery seemed to be ok, second incident happened while driving at night, and I noticed the headlights remained bright.
4)Problem only occurred when engine was warm, as the engine dying occurred more often, it would re-start once the engine was allowed to cool for a short period.
5)No Engine light trouble code came on.

Jeep had original sensor, they are susceptible to high temp failure.  They are known to read normal when cool and tested with an volt meter. Replaced the crankshaft sensor and immediately cleared the problem.  For good measure, also replaced the camshaft sensor.  Engine runs much smoother and feels stronger, on the plus side, MPG increased by at least 4 miles up to 18 from 14 MPG.

Recommend to replace both sensors even if no symptoms are showing, both can be had for about $120 if you shop around.  It is so worth it to avoid having to be towed. Think of it as preventative maintenance.
998279
Check engine light on, error code 420, 430 signaled catalytic converter needs to be replaced. Catalytic converter meant to last the life of car. The sound in exhaust not smooth, loud and rattling. Situation worse because I have a 2005 Audi TT and all parts and repairs are 2-3 Xs higher than American made cars. Got quotes up to $3000 for new catalytic converter. Researched 2 possibilities  1. CATACLEAN (50% of people who tried it check engine light did not return and car ran smoother.... 2. Video on Youtube -Scotty Kilmer -Fix Catalytic converter put 1 gallon of lacquer thinner in fuel tank ...(sounds extreme but most who did this it worked for them). In both cases Cataclean and Lacquer thinner should be added when fuel is at 1/4 full. Reason is both cataclean and lacquer thinner will be at higher concentrations and will burn hotter and burn out the carbon debris in catalytic converter... Also to get the best effect run vehicle at high speed 55 plus  on highway for 30 minutes ... I had to repeat catcalling 2 times and my check engine light did not go off as some people did. So I took negative cable off battery and reattached it (Have radio code available if you do this). Check engine light did not go on (so far 250 miles ). I had tried reseting check engine light and it came back on in less then 50 miles. Car does not have rattling sound is quieter and runs smooth-big difference !!! Runs like new and has over 100,000 miles !!! So cataclean worked for me and if it didn't I would have tried lacquer thinner. Some reviewers say that both substances have acetone ... and can ruin rubber, plastic but 10s of thousands of people have used this and no reported damage seen in my research. All I know is car running great and saved more than  $2000. Will update if check engine light comes on.
2540853
Do yourself a favor and buy a (more expensive) oem sensor, had one of these fail on me in 1000 or so miles just happened to be about 500 miles from my house on a road trip. Luckly I was able to make it home, purchased another one and still have a check engine light due to the sensor, BMW is very finicky with sensors apparently.