Hi i have a 99 hyundia elantra my check engine light is on the codes are p1624,p0137,p0732and p0740 are these codes connected or different problems

Go to google and type each one in separtley and it will tell you why and the causes Jeff.

That is because the check light indicated on OBD2
System Fault

You replaced a part based on the code

The codes are used to diagnose the system that set
the code & then component test

You apparently didn't diagnose the real cause of the
possible problem

The sensor may have been just doing it's job

When you come here either give use the codes or
just Google them to learn the ins & outs

Hi there:
DTC P1624 - MIL Request Signal active


This code is only the TCM (Transmission Control Module) telling the ECM (Engine Control Module) to turn on the check engine light.

If you don't have other codes there, could be a Communication Lost from the TCM; first I suggest to check all fuses and good harnesses conections correctly.



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Essentially the same as P0136, P0137 refers to the second oxygen sensor on Bank 1. P0137 means the O2 oxygen sensor's voltage remained low for longer than 2 minutes. This, is interpreted by the ECM as a low voltage condition and sets the MIL. Bank 1 Sensor 2 is located to the rear of the catalytic converter and should produce an output signal relative to oxygen storage capacity of the catalytic converter. This rear (sensor 2) sensor is less active than the signal produced by the front sensor. However, if the ECM senses the sensor is inactive, this code will set.

There may be no visible symptoms to the driver, other than the MIL (Check Engine / Service Engine Soon) illumination.

A code P0137 may mean that one or more of the following has happened:
Faulty o2 sensor Exhaust leak near the rear sensor
Plugged catalyst
Short to voltage on O2 signal circuit
High resistance or open on O2 signal circuit

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No just after you get it installed be sure to crank it and let it warm up and then check the fluid.

P2251 L.O2 reference circuit(-) open-Sensor 1. This code is showing a problem on the reference voltage of the upper O2 sensor. It might be sensor or the wiring. P0304 Cyl.number 4 Misfire detected. This code is showing 4th.cylinder is or has been missing. Second code might be set by first code.O2 sensor problem needs to be corrected first.

sounds like the air flow meter

Many possible causes for this. Do you have a "Check Engine" light? Whenever the 'CHECK ENGINE' light comes on, the ECU (Engine Control Unit) sets a Diagnostic Trouble Code (DTC). These codes identify the particular engine management system which caused the light to come on.
You'll need to use/find an OBDII (On-Board Diagnostic) Scanner to retrieve any code which have been stored in the ECU computer. Afterward, we might be able to help you DIAGNOSE the problem and perhaps eventually fix the problem.
Soot/Carbon buildup on plugs can be caused by many things, like leaky intake valve seals, excessive crankcase emissions being sent back into the intake air hose, leaky fuel injectors causing an excessively "RICH' fuel mixture, excessive fuel pressure from the fuel pump, faulty fuel pressure regulator, worn/faulty PCV, a faulty O2 sensor (upstream) or even a defective ECU.

DTC P0734 is "4th gear incorrect ratio" - that's your torque converter 'LOCK UP Clutch" It's worn out (or you're using the wrong Trans Fluid required by Hyundai - SPIII OR Both). The P1624 is simply the Trans Control Unit (computer) communicating to the Engine Control Module (ECM computer) MIL - on request signal to ECM = asking it to turn on "Check Engine" light. MIL = Malfunction Indicator Lamp. When the torque converter 'lock up" clutch slips or doesn't engage, the trans automatically returns to 3rd gear and stays there (it's called 'fail safe' mode) until you cycle the ignition key, then everything resets until the malfunction occurs again.
You'll need to have an AT (Automatic Transaxel) tester hooked up to verify this. Hyundai has a Service Bulletin specifically for "gear incorrect ratio' codes. If when you changed the trans fluid, was it done at a Hyundai Service Center? If not, someone may have installed the wrong fluid.

When the check engine light flashes, It's not giving out codes. It is telling you that the engine is misfiring on 1 or more cylinders. New plugs and wires might fix your problem.