Corolla, Auris, Avensis. Bulletproof unit; older 1ZZ versions could burn oil, which sometimes takes the catalyst and O2 sensors with it.
Click a code for the full breakdown: symptoms, causes, and whether you can keep driving.
System Too Lean (Bank 1)
The engine is getting too much air or too little fuel on bank 1 - the ECU has hit the limit of its ability to compensate.
Catalyst System Efficiency Below Threshold (Bank 1)
The downstream oxygen sensor shows the catalytic converter on bank 1 is no longer cleaning exhaust gases efficiently.
Random/Multiple Cylinder Misfire Detected
The engine control unit detects misfires occurring randomly across multiple cylinders, meaning combustion is failing intermittently in more than one cylinder.
Cylinder 1 Misfire Detected
Combustion is repeatedly failing in cylinder 1. The ECU counts crankshaft speed fluctuations and attributes them to that specific cylinder.
Camshaft Position Timing Over-Advanced (Bank 1)
The intake camshaft timing is more advanced than commanded - the variable valve timing system is not responding correctly.
Engine Control System Malfunction (ABS/VSC Interlock - Toyota/Lexus)
On Toyota/Lexus vehicles, the ABS/stability system disables itself because the engine ECU reported a fault. C1201 accompanies an engine code.
EVAP System Leak Detected (Large Leak)
The fuel vapor recovery system has a significant leak - most often the fuel cap is loose or missing.
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