本页暂无Chinese版本，以下为英文原文。 查看英文版 →
OBD2 故障码库
102 个故障码，包含定义、按概率排序的成因、故障现象以及由俭入繁的维修顺序。每一条都由造工具的工程师撰写——没有套话。
热门查询
修理厂每天查的 8 个码 P0301 Cylinder 1 Misfire Detected P0101 Mass Air Flow Circuit Range / Performance P0440 Evaporative Emission Control System Malfunction P0455 Evaporative Emission Control System Leak Detected (Gross Leak) P0011 Intake Camshaft Position Timing — Over-Advanced (Bank 1) P0135 O2 Sensor Heater Circuit Malfunction (Bank 1 Sensor 1) C0035 Left Front Wheel Speed Sensor Circuit P0217 Engine Overheat Condition
最难故障码的深度指南
8 个码在知识中心有带真实案例数据的完整诊断流程。从码页外链出去，两个页面不会互相抢排名。
P0xxx — 动力总成（P）
44 个故障码发动机、变速箱与排放——修理厂每天都会遇到的码。
P0010 Intake Camshaft Position Actuator Circuit / Open (Bank 1) The ECU commands the variable valve timing solenoid on the intake cam but sees no electrical response — open circuit, short, or a dead solenoid. On most engines this freezes cam timing at the default position. 中严重度 P0011 Intake Camshaft Position Timing — Over-Advanced (Bank 1) The actual intake cam angle is more advanced than the commanded target for a set time. Usually a sticking actuator, oil pressure problem, or a stretched timing chain rather than an electrical fault. 中严重度 P0016 Crankshaft / Camshaft Position Correlation (Bank 1 Sensor A) The relative position between crank and cam is outside the learned window. This is a mechanical timing problem until proven otherwise — stretched chain, jumped tooth, or a badly worn tensioner. 高严重度 P0030 HO2S Heater Control Circuit (Bank 1 Sensor 1) The upstream oxygen sensor's internal heater is not drawing the expected current. The sensor then warms slowly, so fuel control stays open-loop longer and emissions and consumption rise. 中严重度 P0101 Mass Air Flow Circuit Range / Performance The MAF reading does not match what the ECU expects for the given RPM, throttle and load. Either the sensor is dirty/out of range, or air is entering the engine without being measured. 中严重度 P0102 Mass Air Flow Circuit Low Input The MAF signal stays below the plausible minimum. The ECU falls back to a speed-density calculation, which keeps the car drivable but with compromised mixture control. 中严重度 P0115 Engine Coolant Temperature Circuit Malfunction The ECT signal is out of range or implausible. The ECU then cannot judge warm-up state, so fuelling, fan control and transmission behaviour all go wrong. 中严重度 P0125 Insufficient Coolant Temperature for Closed Loop Fuel Control The engine has been running long enough that it should be in closed-loop fuel control, but the ECU never sees the coolant reach the expected temperature. Almost always a thermostat that is stuck open. 低严重度 P0131 O2 Sensor Circuit Low Voltage (Bank 1 Sensor 1) The upstream oxygen sensor output stays near zero volts — the ECU reads permanent lean. Left alone this drives fuel trims rich and can destroy the catalyst. 中严重度 P0133 O2 Sensor Circuit Slow Response (Bank 1 Sensor 1) The sensor still switches, but too slowly to control mixture properly. A classic ageing symptom — the sensor is tired, not dead. 低严重度 P0135 O2 Sensor Heater Circuit Malfunction (Bank 1 Sensor 1) The heater inside the upstream sensor is not working, so the sensor takes far too long to reach operating temperature and closed-loop control is delayed. 低严重度 P0172 System Too Rich (Bank 1) Fuel trims have gone strongly negative — the ECU is pulling fuel to compensate for too much of it. The engine is running rich, not lean. 中严重度 P0174 System Too Lean (Bank 2) Bank 2 fuel trims are strongly positive — the ECU is adding fuel because the mixture is too lean on that side of the engine. 中严重度 P0201 Injector Circuit Malfunction — Cylinder 1 The ECU detects an electrical problem on the cylinder 1 injector driver circuit: open, short, or a coil that is out of specification. 高严重度 P0217 Engine Overheat Condition Coolant temperature exceeded the protective threshold. The ECU often cuts fuel or disables cylinders to protect the engine — take this seriously. 高严重度 P0234 Turbocharger / Supercharger Overboost Condition Actual boost pressure exceeds the commanded target. Common on electronically controlled wastegates and variable-geometry turbos with sticking mechanisms. 高严重度 P0301 Cylinder 1 Misfire Detected Cylinder 1 is not contributing power consistently. Unlike a random misfire, this is isolated to one cylinder — so swap-testing parts will find it fast. 高严重度 P0302 Cylinder 2 Misfire Detected Cylinder 2 is misfiring. The diagnostic logic is identical to P0301 — the cylinder number simply tells you where to start looking. 高严重度 P0303 Cylinder 3 Misfire Detected Cylinder 3 misfire. Same diagnostic approach as other cylinder-specific misfire codes: confirm the cylinder, then swap-test to move the fault. 高严重度 P0304 Cylinder 4 Misfire Detected Cylinder 4 misfire. Swap-test ignition and fuel components first; compression last. This is the most reliable way to avoid replacing good parts. 高严重度 P0315 Crankshaft Position System Variation Not Learned The ECU has lost its learned crankshaft position variation values, which it uses to detect misfire accurately. Common after an ECU replacement, a flywheel change or a software update. 低严重度 P0325 Knock Sensor 1 Circuit Malfunction (Bank 1) The knock sensor signal is missing or out of range, so the ECU cannot detect detonation and will typically retard ignition timing as a protective default. 中严重度 P0335 Crankshaft Position Sensor A Circuit Malfunction No usable crank signal. Without it the ECU cannot time injection or ignition, so the engine will usually crank without starting. 高严重度 P0340 Camshaft Position Sensor Circuit Malfunction No usable cam signal. Most engines will still start using the crank signal alone, but with sequential injection and VVT disabled. 中严重度 P0351 Ignition Coil A Primary / Secondary Circuit Malfunction The ECU monitors the coil primary circuit for cylinder 1 and sees a fault — open, short, or a coil that does not draw the expected current. 高严重度 P0380 Glow Plug / Heater Circuit A Malfunction A diesel cold-start aid circuit is open or drawing wrong current. Cold starts become hard and smoky, especially in winter. 中严重度 P0402 Exhaust Gas Recirculation Flow Excessive Detected Too much exhaust gas is entering the intake. The EGR valve is stuck open or the flow signal is over-reading, starving the mixture of oxygen. 中严重度 P0403 Exhaust Gas Recirculation Control Circuit Malfunction An electrical fault in the EGR solenoid or motor circuit — no control, so the ECU cannot modulate EGR at all. 中严重度 P0405 Exhaust Gas Recirculation Sensor A Circuit Low The EGR position sensor voltage is below its plausible minimum — a short to earth, an open reference, or a dead sensor. 中严重度 P0430 Catalyst System Efficiency Below Threshold (Bank 2) The bank 2 catalytic converter is no longer storing enough oxygen to smooth the exhaust — the downstream sensor is switching too much like the upstream one. 中严重度 P0440 Evaporative Emission Control System Malfunction The EVAP system failed its overall integrity check. Fuel vapour is escaping somewhere between the tank and the charcoal canister. 低严重度 P0441 Evaporative Emission Control System Incorrect Purge Flow The ECU commanded the purge valve open but the expected change in fuel trims or tank pressure did not occur — a flow problem rather than a leak. 低严重度 P0442 Evaporative Emission Control System Leak Detected (Small Leak) A small leak — typically equivalent to a 0.5–1 mm hole. Harder to find than a gross leak, and the smoke machine is the only realistic tool. 低严重度 P0455 Evaporative Emission Control System Leak Detected (Gross Leak) A large leak — the system cannot hold any pressure at all. Usually an obvious physical fault: missing cap, split hose, or a disconnected line. 低严重度 P0500 Vehicle Speed Sensor Circuit Malfunction No vehicle speed signal reaching the ECU or instrument cluster. Transmission shifting, speedometer and stability systems all depend on this input. 中严重度 P0507 Idle Control System RPM Higher Than Expected The engine idles above the target speed and the ECU cannot bring it down. Either extra air is getting in, or the throttle is not closing as commanded. 中严重度 P0524 Engine Oil Pressure Too Low The oil pressure switch or sensor indicates pressure below the safe threshold. This is a stop-the-engine code — running further can destroy bearings. 高严重度 P0563 System Voltage High The ECU sees charging voltage above roughly 16 V. Overcharging boils the battery and can damage sensitive electronics across the vehicle. 高严重度 P0606 ECM / PCM Processor Fault The engine control module's internal self-check has failed. Before replacing an ECU, exhaust every external cause — most of these turn out to be power or earth problems. 高严重度 P0620 Generator Control Circuit Malfunction The ECU commands the alternator but does not see the expected response — typical on smart-charging systems where the regulator is ECU-controlled. 中严重度 P0700 Transmission Control System Malfunction A generic flag telling you the transmission ECU has stored a fault. Read the TCU's own codes to find the real problem. 中严重度 P0705 Transmission Range Sensor Circuit Malfunction (PRNDL Input) The ECU cannot determine which gear the selector is in, or sees an implausible combination. The vehicle may refuse to start or start in any position. 高严重度 P0730 Incorrect Gear Ratio The ECU compares input and output shaft speeds and finds a ratio that does not match the commanded gear — the transmission is slipping. 高严重度 P0741 Torque Converter Clutch Circuit Performance / Stuck Off The torque converter lock-up clutch is not applying when commanded. The engine revs higher than it should at steady cruise and fuel economy suffers. 中严重度
B0xxx — 车身（B）
20 个故障码安全气囊、车身控制模块、空调、照明与进入系统。
B0001 Driver Frontal Stage 1 Deployment Control A fault in the driver's frontal airbag first-stage deployment loop. This is a safety system — the airbag will not fire correctly until it is repaired. 高严重度 B0010 Passenger Frontal Stage 1 Deployment Control Fault in the passenger frontal airbag deployment loop. Same safety-critical handling as B0001, on the passenger side. 高严重度 B0020 Left Side Airbag Deployment Control Fault in the left-side airbag or curtain deployment loop. Usually the connector under the seat or in the door pillar. 高严重度 B0050 Passenger Airbag Disable Indicator Circuit The lamp or circuit that shows passenger airbag status has failed. The airbag itself may still be functional, but the driver cannot confirm its state. 中严重度 B0080 Passenger Presence / Occupant Classification System The system that decides whether an adult is sitting in the passenger seat has failed. The airbag is typically suppressed as a precaution. 中严重度 B0090 Restraint System Crash Sensor Fault One of the impact sensors feeding the airbag ECU is out of range or not communicating. Deployment logic becomes unreliable. 高严重度 B0100 Airbag Disable Switch Circuit Fault in the manual passenger airbag on/off switch circuit (where fitted). The system cannot confirm the requested suppression state. 中严重度 B0110 Seat Belt Pretensioner Circuit Fault A fault in the pyrotechnic or electric seat belt pretensioner circuit. The belt will not tighten correctly in a crash. 高严重度 B0159 Outside Air Temperature Sensor Circuit The ambient temperature sensor is open, shorted or reading implausibly. Automatic climate control and some driver displays depend on it. 低严重度 B0160 Cabin Temperature Sensor Circuit The in-car temperature sensor used by automatic climate control is out of range, so the system cannot regulate cabin temperature accurately. 低严重度 B0170 Evaporator Temperature Sensor Circuit The evaporator temperature sensor reading is implausible. The A/C compressor then cannot be modulated correctly, risking evaporator icing. 低严重度 B1000 Body Control Module Internal Fault A generic body-module self-check failure. Manufacturer-specific above the SAE range — read the module's own extended data before acting. 中严重度 B1200 Climate Control Module Serial Data / Panel Fault The climate control panel has lost communication or failed internally. Often a power or data-line issue rather than a dead panel. 低严重度 B1318 System Voltage Low (Body Module) The body module has seen supply voltage below its operating threshold. Always find the cause — a weak battery sets this long before it fails to start. 中严重度 B1325 System Voltage Out of Range The body module has seen voltage either too low or too high. Check the charging system in both directions before replacing anything. 中严重度 B1342 ECU Internal Fault / Memory Error (Body Module) The body module flagged an internal memory or processor error. Like all internal-fault codes, external power problems come first on the list. 中严重度 B1350 Airbag Deployment Loop / Squib Circuit Resistance Out of Range Resistance in a restraint deployment loop is outside specification. Even a small extra resistance can prevent deployment. 高严重度 B1500 Seat Belt Switch / Buckle Circuit Fault The buckle switch that tells the vehicle whether the belt is fastened is not reporting correctly, affecting warnings and restraint strategy. 中严重度 B1600 Immobilizer / Key Transponder Communication Fault The immobilizer cannot read a valid key transponder, so the engine is prevented from starting. A no-start code, not a running fault. 高严重度 B2200 Anti-Theft / Key Data Mismatch Stored key data does not match what the immobilizer or body module expects — typical after a module swap or an interrupted programming session. 高严重度
C0xxx — 底盘（C）
20 个故障码ABS、ESP、转向、悬架与线控制动系统。
C0035 Left Front Wheel Speed Sensor Circuit No usable signal from the left front wheel speed sensor. ABS and stability control are disabled as soon as one wheel is unknown. 高严重度 C0040 Right Front Wheel Speed Sensor Circuit Right front wheel speed signal lost or implausible. ABS, traction and stability functions are disabled. 高严重度 C0050 Left Rear Wheel Speed Sensor Circuit Left rear wheel speed signal lost. On rear sensors, also check for hub bearing wear changing the air gap. 高严重度 C0060 Rear Axle Steering / Differential Control Circuit Fault in an electronically controlled rear steering or locking differential actuator. Handling aids are disabled, base driving remains. 中严重度 C0110 ABS Pump Motor Circuit Malfunction The ABS hydraulic pump motor does not run or draws wrong current. The system cannot build pressure for ABS or stability intervention. 高严重度 C0121 Brake Fluid Pressure / Differential Pressure Switch Fault The pressure differential switch indicates an imbalance between brake circuits — a genuine hydraulic warning, not an electronics nuisance. 高严重度 C0200 Steering Angle Sensor / Transfer Case Range Fault The steering angle signal is missing, out of range or not learned. Stability control and electric power steering assistance depend on it. 高严重度 C0210 Yaw Rate / Lateral Acceleration Sensor Fault The sensor that tells the ESP module how the car is actually rotating is not reporting correctly, so stability control is disabled. 高严重度 C0220 Right Rear Wheel Speed Sensor Circuit Right rear wheel speed signal lost. ABS and stability functions disabled until all four wheels report reliably. 高严重度 C0230 Brake Booster / Vacuum or Electric Assist Sensor Fault The brake assist system cannot verify booster performance. Pedal effort may increase and braking distances can lengthen. 高严重度 C0240 Traction Control Engine Torque Request Circuit The traction control module cannot request torque reduction from the engine — a coordination fault rather than a mechanical one. 中严重度 C0265 ABS/ESP Control Module Relay or Power Circuit The ABS module's power supply or internal relay is not behaving. A supply problem masquerading as a module failure in most cases. 高严重度 C0280 Brake Pedal Position / Travel Sensor Fault The ECU cannot trust the brake pedal input, which affects brake light operation, regenerative blending on hybrids and EVs, and stability logic. 高严重度 C0300 Steering / Suspension Actuator Circuit Fault Fault in an electronically controlled damping or steering actuator. Ride height or steering assist may be stuck at a default. 中严重度 C0500 Electronic Steering / Suspension Control Module Fault Internal fault in the steering or suspension control module. Verify power, earth and configuration before replacing hardware. 高严重度 C0550 ECU / Module Not Configured or Configuration Mismatch A chassis module has no valid configuration or the vehicle data does not match. Typical after a used-module swap or an interrupted coding session. 中严重度 C0561 System Disabled / Calibration Data Not Available A chassis function is disabled because required calibration data is missing — common after ADAS or steering work. 中严重度 C1100 Chassis Control Module Power / Internal Fault Generic chassis module fault. As with every internal-fault code, rule out supply, earth and water before replacing anything. 高严重度 C1200 ABS / Traction Control System Disabled (Torque Request Rejected) The chassis module asked the engine ECU to reduce torque and the request was refused or timed out — usually a network or coding issue between modules. 中严重度 C1230 Stability System Longitudinal Acceleration Sensor Fault The longitudinal acceleration input used by stability and hill-hold functions is missing or implausible. 中严重度
U0xxx — 网络通信（U）
18 个故障码控制模块之间的 CAN / LIN / FlexRay 总线通信。
U0001 High Speed CAN Communication Bus The high-speed CAN bus is off-line or badly degraded. Multiple modules lose contact at once — which is the clue that tells you it is the bus, not a module. 高严重度 U0002 High Speed CAN Communication Bus Performance The bus still works but with errors, retries or degraded signal quality. Far more common than a total bus failure and much harder to spot. 中严重度 U0010 Medium Speed CAN Communication Bus The medium-speed CAN bus (typically body/comfort functions) is down. Drivability usually survives, but body functions drop out. 中严重度 U0020 Low Speed CAN / LIN Bus Communication Fault on a low-speed or single-wire LIN bus. These carry simple devices: mirrors, seat modules, rain sensors, alternator control. 低严重度 U0073 Control Module Communication Bus Off A module has shut down its CAN transmitter, often as self-protection after persistent errors. It may be a symptom rather than the root cause. 高严重度 U0101 Lost Communication with TCM (Transmission Control Module) The engine ECU cannot talk to the transmission controller. The gearbox usually defaults to limp mode or refuses to engage. 高严重度 U0110 Lost Communication with Drive Motor / Inverter Control Module On hybrids and EVs, the main ECU has lost contact with the inverter or motor controller. The vehicle will not drive or will not ready-up. 高严重度 U0121 Lost Communication with ABS / ESP Control Module The ABS module has dropped off the bus. Stability and traction functions are gone, and other modules usually complain too. 高严重度 U0129 Lost Communication with Brake System Control Module Communication with the brake control module is lost. On vehicles with integrated braking (regenerative or brake-by-wire) the effect is more severe than on conventional systems. 高严重度 U0131 Lost Communication with Power Steering Control Module The steering control module is not responding. Assist usually drops to a reduced default rather than disappearing entirely. 高严重度 U0140 Lost Communication with Body Control Module The body module has dropped off the bus, taking lighting, locking, windows and wipers with it in one go. 中严重度 U0155 Lost Communication with Instrument Panel Cluster The cluster is off-line. Besides the obvious display loss, the cluster is often the gateway between buses — its absence can silence other modules. 中严重度 U0164 Lost Communication with HVAC Control Module The climate control module is not responding. Usually a comfort problem rather than a drivability one — except on EVs where it manages battery thermal control. 低严重度 U0184 Lost Communication with Radio / Infotainment Module The head unit has dropped off the bus. Rarely affects driving, but on fibre-optic (MOST) systems one dead node can silence the whole ring. 低严重度 U0293 Lost Communication with Hybrid / EV Battery Energy Control Module The battery management controller is not responding. The vehicle will not ready-up, and this is high-voltage territory. 高严重度 U0401 Invalid Data Received from ECM / PCM A module received data from the engine ECU that it considers invalid — often a software version or coding mismatch rather than a wiring fault. 中严重度 U0415 Invalid Data Received from ABS Control Module Another module received implausible data from the ABS module. Stability, steering and ADAS functions may all be limited as a result. 高严重度 U0422 Invalid Data Received from Body Control Module A module received implausible body data — typically lighting, door or vehicle-configuration information that does not match. 低严重度