Support · Fault Code Lookup

OBD-II Fault Code Guides

Mechanic-written repair guides for every trouble code — what it really means, what actually causes it, and how to fix it before you replace expensive parts.

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P014A Code O2 Sensor Delayed Rich-to-Lean Response P0350 Code Ignition Coil Primary/Secondary Circuit P2753 Code Transmission Fluid Cooler Control Circuit Open P2837 Code Shift Fork B Position Range/Performance P2542 Code Test the Low-Pressure Fuel Sensor High CircuitDTC P0775 Code Pressure Control Solenoid B Diagnosis P0147 Code O2 Sensor Heater Circuit (Bank 1 Sensor 3) P0552 Code Power Steering Pressure Sensor Circuit Low Input P0977 Code Test Shift Solenoid B Control Circuit HighDTC P2433 Code Test the Secondary Air Pressure Sensor High CircuitDTC P062D Code Test Fuel Injector Driver Performance Bank 1DTC P0313 Code Diagnose Misfire Detected With Low FuelDTC P2179 Code Diagnose System Too Lean Off Idle Bank 2DTC P000A Code A Camshaft Position Slow Response Bank 1 P0A43 Code Drive Motor A Position Sensor Circuit Intermittent P0778 Code Pressure Control Solenoid B Electrical P0672 Code Cylinder 2 Glow Plug Circuit/Open P0051 Code HO2S Heater Control Circuit Low, Bank 2 Sensor 1 P2706 Code Shift Solenoid F Diagnosis P040D Code EGR Temperature Sensor A Circuit High P0508 Code Idle Air Control System Circuit Low P0840 Code Transmission Fluid Pressure Sensor/Switch A Circuit P025A Code Fuel Pump Module A Control Circuit/Open P0598 Code Thermostat Heater Control Circuit Low P054B Code Cold-Start Exhaust Cam Timing Over-Retarded, Bank 1 P2BA9 Code Insufficient Reductant Quality and DEF Diagnosis P0935 Code Hydraulic Pressure Sensor Circuit High P2800 Code Transmission Range Sensor B Circuit Diagnosis P0877 Code Transmission Pressure Sensor/Switch D Circuit Low P014C Code O2 Slow Response, Rich to Lean — Bank 1 Sensor 1 P2787 Code Clutch Temperature Too High — Causes and Checks P2765 Code Input/Turbine Speed Sensor B Circuit Diagnosis P228F Code Fuel-Pressure Regulator 1 Learning Too High P2420 Code EVAP Switching Valve Control Circuit High P0503 Code Vehicle Speed Sensor A Intermittent, Erratic or High P2229 Code Barometric Pressure Sensor A Circuit High P0755 Code Shift Solenoid B Electrical Malfunction P2300 Code Ignition Coil A Primary Control Circuit Low P023B Code Charge-Air Cooler Pump A Circuit Low P0481 Code Cooling Fan 2 Control Circuit Diagnosis P0240 Code Boost Sensor B Circuit Range/Performance P0231 Code Fuel Pump Secondary Circuit Low P007D Code Charge-Air Cooler Temperature Sensor High P0464 Code Fuel Level Sensor A Circuit Intermittent P2074 Code MAP/MAF–Throttle Correlation at Higher Load P2088 Code A Camshaft Actuator Control Circuit Low Bank 1 P0342 Code Camshaft Position Sensor A Circuit Low Input P0934 Code Hydraulic Pressure Sensor Circuit Low P2757 Code TCC Pressure Control Solenoid Performance/Stuck Off P0550 Code Power Steering Pressure Sensor/Switch Circuit
655 codes · page 1 of 14
01 Read your code

Every code is four signals in five characters.

P
System
P = Powertrain (engine & transmission)
0
Type
0 = generic SAE standard · 1 = make-specific
4
Subsystem
The subsystem the code points to
2
Fault
The specific fault
0
Index
Index within that subsystem
P
Powertrain

Engine, fuel, ignition, emissions and transmission. By far the most common — most check-engine lights start with P.

B
Body

Interior comfort and safety: airbags, lighting, power windows, seats, climate control.

C
Chassis

Mechanical systems outside the body: ABS, traction control, steering, suspension, wheel-speed sensors.

U
Network

Communication between control modules over the car's data bus (CAN). Often points to wiring or a module that has gone quiet.

Generic vs manufacturer-specific: a 0 in the second position means the code follows the SAE standard and means the same on every car — those are the ones in this library. A 1 (and sometimes 3) means the carmaker defined it themselves, so the same code can mean different things on a BMW and a Toyota. For those, read the exact definition on your scan tool.

02 When the light comes on

Four moves, in order.

  1. Is it flashing?

    A flashing check-engine light usually means an active misfire that can damage the catalytic converter — ease off the throttle and get it looked at promptly. A steady light is rarely an emergency; investigate soon.

  2. Scan for the codes

    Plug in a scan tool and read the stored codes. Note every code and its freeze-frame data — the first one set is often the root cause of the rest.

  3. Look it up

    Search the code here to understand what system it points to, how serious it is, and the parts most often behind it — before you spend a cent on parts.

  4. Fix, clear, confirm

    Repair the root cause, clear the code, then drive and re-scan. If it comes straight back, the underlying fault is still there — keep diagnosing, don't just keep clearing.

From code to cause

A code tells you the system. A scanner tells you the part.

Reading the code is step one. ICARZONE tools go further — live data, bidirectional actuator tests and OE-level access pinpoint the actual faulty component, then clear the code once it's fixed.

Explore the toolsCompare models

Can't find your code, or got a P1/B1/C1/U1 code? Those are manufacturer-specific. Tell our team the code and your vehicle (make, model, year) and we'll help you read it — or grab the exact OE definition with an ICARZONE tool. Contact support →