MotorBitMost searched codes
P0300
Random/Multiple Cylinder Misfire Detected
The engine is misfiring across more than one cylinder. This is one of the most common reasons a check engine light flash…
P0420
Catalyst System Efficiency Below Threshold (Bank 1)
The catalytic converter on bank 1 is not cleaning exhaust as efficiently as the PCM expects. This is a top search OBD2 c…
P0171
System Too Lean (Bank 1)
Bank 1 is running lean — too much air or not enough fuel. A very common check engine light on many brands.…
P0442
EVAP System Leak Detected (Small Leak)
A small evaporative emissions leak, often a loose gas cap. The light can take days of driving to return after you tighte…
P0128
Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature)
The engine is not reaching normal temperature quickly enough. A stuck-open thermostat is the usual cause.…
P0401
EGR Flow Insufficient Detected
Exhaust gas recirculation flow is lower than commanded. Carbon-clogged EGR passages are extremely common.…
P0135
O2 Sensor Heater Circuit Malfunction (Bank 1 Sensor 1)
The upstream oxygen sensor heater on bank 1 failed. The light can come on shortly after startup.…
P0700
Transmission Control System Malfunction
A request from the transmission controller. P0700 is a pointer code — there is usually a more specific TCM code stored.…
P0335
Crankshaft Position Sensor A Circuit Malfunction
Crank sensor circuit fault. This can cause no-start, stalling, or a sudden cut-out.…
Guides that rank for real searches
LIGHT
Why is my check engine light on?
Steady vs flashing, what to do in the first 10 minutes.
SCAN
How to read OBD2 codes on iPhone
ELM327 setup, what freeze frame is, when to clear codes.
GEAR
What is an ELM327 adapter?
Bluetooth vs cheap clones, and what MotorBit supports.
DATA
Freeze frame explained
The snapshot the ECU saved when the fault set.
Why MotorBit
Built for diagnosis
Codes, live PIDs, charts, monitors, freeze frame, fuel trim — not just a generic code reader screen.
Privacy first
Vehicle data stays on your iPhone. No account required to scan.
ELM327 ready
Works with common Bluetooth OBD2 dongles. Pair, scan, understand the light.