2003 c230 PO303 shaking and fuel inefficiency
09-05-2011, 03:37 AM
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2003 c230 PO303 shaking and fuel inefficiency
I bought 2003 c230 coupe which has 104k miles and it was giving bad sound and shake and i took it dealer and they told me i need to change the belt tensioner and they changed however bad sound gone but shake is still there. today i went to O'Reilly and diagnosed and it showed me these codes
PO303 CYLINDER 3 MISFIRE
PO141 02 SENSOR HEATER CIRCUIT
PO136 02 SENSOR CIRCUIT
PO410 SECONDARY AIR INJECTION SYSTEM MALFUNCTION
I read a lot about it since the car shakes a lot sometimes and it seems like one of the cylinder (#3) misfires and i get really bad mpg (17 on highway) after it started to shake if i stop the car and restart it goes away.
i used those injector cleaners but it really did not help.
what should i do in this case?
thanks for answers.
PO303 CYLINDER 3 MISFIRE
PO141 02 SENSOR HEATER CIRCUIT
PO136 02 SENSOR CIRCUIT
PO410 SECONDARY AIR INJECTION SYSTEM MALFUNCTION
I read a lot about it since the car shakes a lot sometimes and it seems like one of the cylinder (#3) misfires and i get really bad mpg (17 on highway) after it started to shake if i stop the car and restart it goes away.
i used those injector cleaners but it really did not help.
what should i do in this case?
thanks for answers.
09-05-2011, 07:41 AM
#2
Super Moderator
Check plug, coil & compression test cylinder 3. Remember to compression test at WOT.
Replace O2 sensors or at least the upstream unit to start with & report outcome.
If you still display a secondary air pump code we will then tackle that.
Good luck!
Replace O2 sensors or at least the upstream unit to start with & report outcome.
If you still display a secondary air pump code we will then tackle that.
Good luck!
