p0171, p0300, p0420 codes!!

[v1ndzl]

i got a 07 corolla from my dad, been driving it for almost 3 months now.. more than a month ago, p0171 and p0300 came on. my car ran rough, almost stalling.. i replaced the spark plugs, one ignition coil which seemed to fix it for a while.

then 2 weeks ago, p0420 came on, then p0171 is back!! i also noticed a ticking noise and some shaking from the engine.. i replaced the fuel injectors and that cleared the codes for a while but p0420 is back again this weekend.

my quick research said that p0420 is an 02 sensor or a bad catalytic converter.. then im thinking there's an exhaust leak coz of the ticking and shaking.

anyone here dealt with this combo of issues? should i start with the converter or the exhaust leak??

 

[sin city priest]

i got a 07 corolla from my dad, been driving it for almost 3 months now.. more than a month ago, p0171 and p0300 came on. my car ran rough, almost stalling.. i replaced the spark plugs, one ignition coil which seemed to fix it for a while.

then 2 weeks ago, p0420 came on, then p0171 is back!! i also noticed a ticking noise and some shaking from the engine.. i replaced the fuel injectors and that cleared the codes for a while but p0420 is back again this weekend.

my quick research said that p0420 is an 02 sensor or a bad catalytic converter.. then im thinking there's an exhaust leak coz of the ticking and shaking.

anyone here dealt with this combo of issues? should i start with the converter or the exhaust leak??

Inspect the exhaust system for leaks as the ticking and shaking could point to a damaged manifold/pipe.

If no leaks are found, test the oxygen sensors and catalytic converter for efficiency.

 

[Belfort09]

I think I've dealt with the same thing before. The ticking and shaking most likely is an exhaust leak, which can mess with O2 sensor readings and cause all those codes. Id start by checking for a leak near the exhaust manifold or flex pipe, fixing that might clear up the P0171 and P0420 without needing a new cat. Do that before replacing the converter.

 

[Tequila.tee]

Before dropping $$ on a new converter, use a smoke test or even a shop rag and your hand to feel for puffs when cold starting and if there's a leak you're gonna know, fix that first, clear the codes, then see what comes back.
Don't throw a cat at it until you've ruled out everything upstream.

 

[GarsaFwip25]

I think I've dealt with the same thing before. The ticking and shaking most likely is an exhaust leak, which can mess with O2 sensor readings and cause all those codes. Id start by checking for a leak near the exhaust manifold or flex pipe, fixing that might clear up the P0171 and P0420 without needing a new cat. Do that before replacing the converter.

Did you end up using a smoke test to find the leak or just go old-school with soapy water? And did the codes stay off after the fix or did they reappear later on?

 

[SmoothOp]

I had a friend who owned an older Matrix that kept throwing the same codes in bursts. At first, he went after the sensors, but it turned out that a tiny crack near the manifold was the actual problem. Once he fixed that up, the codes stopped appearing. I'd suggest starting with that as well