2003 c230 PO303 shaking and fuel inefficiency
Thread Starter
Newbie
Joined: Jul 2011
Posts: 6
Likes: 0
c230 k
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.
Super Moderator
Joined: Jun 2008
Posts: 19,942
Likes: 192
From: Llandudno, Cape Town, South Africa
late 2009 CLK 350 Coupe Elegance, '65 Jaguar S Type wires
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!
