Check engine light and loss of power!!

Messages
1,180
Location
Berks County/Pa.
Was with good friend of mine yesterday. Driving in his 2008 Hyundai Sonata 2.4L 119,xxx miles -- car bucked out of nowhere 3 times and check engine light came on immediately. He pulled over to the side of the road -- turned car off and checked all fluids which were all at proper full levels. Restarted the car and he said this thing has no power right now. Went directly home and parked the car. I personally noticed that the car sounded to have an exhaust leak when he initially started it before the bucking/check engine light illuminated. After he restarted the car -- no longer hearing the exhaust leak at all?? Were both stumped at the moment -- said hes gonna take it to his mechanic tomorrow and get the OBD 2 reader on it. What for thoughts do use have overall on this issue please.
 
Messages
3,049
Location
The Northeast
Code(s) will say for sure but probably a misfire. It can cause a *putt-putt-putt* noise from the tailpipe which can sound like an exhaust leak.

Those Hyundai 2.4's have known problems so hopefully it's nothing serious....
 
Messages
5,350
Location
NJ
Need to get a cheap OBD2 reader. Some codes will cause the ECU to shut things down to avoid damage to other parts. I cleaned the MAF sensor and forgot to plug it back in. Car threw codes and went into jog mode and wouldn't go above 3000rpm. The bucking and lack of power might not be a symptom of the actual problem. Could be a sensor that went out that the ECU needs to have to run things properly. Let us know what the code is.
 
Messages
74
Location
Los Gatos, CA
First thought is do not drive a car when the check engine light goes on until you’ve read and understood that code. Your friend shouldn’t have driven home. Sorry if you agree and I’m preaching to the choir. As wild guesses go last time I had something like that it was both upstream O2 sensors and 1 of 4 catalytic converters kinda clogged but it could be many things. Thankfully in that case the OBD codes basically handed me the diagnosis. Cataclean fixed the cat and I put in two new O2 sensors. Gumout Multi (PEA/Techron) into the fuel tank for good measure.
 
Messages
4,167
Location
Texas
Need to get a cheap OBD2 reader. Some codes will cause the ECU to shut things down to avoid damage to other parts. I cleaned the MAF sensor and forgot to plug it back in. Car threw codes and went into jog mode and wouldn't go above 3000rpm. The bucking and lack of power might not be a symptom of the actual problem. Could be a sensor that went out that the ECU needs to have to run things properly. Let us know what the code is.
Yes . Code readers can be had for $25 - $50 , & you own it for now on . Or go to O'Reilly , autoZone , Advance or , maybe NAPA and get the codes read for free .
 

JTK

Messages
13,289
Location
Buffalo, NY
Was the check engine light *flashing* by chance?

If so, that would indicate a misfire which you wouldn't want to drive the vehicle any more than you absolutely need to.
 

Nick1994

$50 Site Donor
Messages
13,006
Location
Phoenix, AZ
My guess is the catalytic converter self destructed. They can break off inside and turn sideways which means basically no flow, happened to my brother's truck.

Those Hyundai 2.4's have known problems so hopefully it's nothing serious....
The 2010 2.4L and prior we're solid. The 2011 and later have the self destruct mode.
 
Last edited:
Messages
2,912
Location
Georgia/Retired
Codes are tripped because of emission faults. As an example, you won't get a CEL when the connecting rod blows through the block, a rod bearing spins or the coolant level is low.

As mentioned above, get the codes read. You'll likely find that either the crank position sensor or one of the camshaft position sensors has become unresponsive. I mention these because the engine has reduced power. You will get a code for a bad oxygen sensor when they're unresponsive or slow to respond but they don't cause a reduced power scenario.
 
Messages
169
Location
Woodbridge, NJ
I'm betting on catalytic convertor plugged. Pull th eupstream O2 sensor and see if it drives. If it does it's the cat. Happened on 2 of my sons cars. The most recent a Hyundai with about the same mileage as OP's

Don
 
Messages
94
Location
Arizona
I had a similar issue with an 05 Santa Fe 2.7L. Mine turned out to be the transmission input AND out speed sensors. Likely one or the other, but I changed both.
Car would buck, no engine power, etc
Not sure if the transaxle is the same or not. But might do a quick search on that.
 
Messages
151
Location
Ontario, Canada
Yes . Code readers can be had for $25 - $50 , & you own it for now on . Or go to O'Reilly , autoZone , Advance or , maybe NAPA and get the codes read for free .
You can also get cheap bluetooth ones that allow you to use an app on a smartphone or tablet. I have the BlueDriver one and it is great to be able to monitor the live data while driving, and it reads all codes including ABS and SRS for most cars.
 
Messages
316
Location
MO, USA
Yes . Code readers can be had for $25 - $50 , & you own it for now on . Or go to O'Reilly , autoZone , Advance or , maybe NAPA and get the codes read for free .
I agree on the misfire and buying your own reader. mine is from HF and works fine. misfires will damage a cat pretty quickly
 
Top