Check engine codes
Plain-English meanings and prices
Type in the code from your scanner or the parts store to see what it means and whether it’s OK to drive. If it’s a job we do, our price is right there too.
Dash decoder
What’s your dash telling you?
Tap the light that’s on, or what the car is doing.
Or what it’s doing
CHECK ENGINE, STEADY
Book soonA stored engine or emissions fault.
It could be a loose gas cap or something bigger, like a misfire. A scan narrows it down, and testing finds the part.
Likely fix · flat labor
Mobile diagnostic$75Common codes
P0420
OK to driveCatalyst System Efficiency Below Threshold (Bank 1)
The catalytic converter on bank 1 isn't cleaning the exhaust as well as it should.
Common causes
- Worn-out catalytic converter
- Faulty downstream oxygen sensor
- Exhaust leak
- Misfires or oil burning that damaged the converter
Don't buy a converter on the code alone. We check the sensors and look for leaks first. If it is the converter, we text you a price first.
What we’d do · flat labor
How to read a code
Every code is five characters. The letter is the system: P powertrain (engine and transmission), B body, C chassis, U network. The first number tells you who defined it: 0 or 2 means generic, the same on every car; 1 means the carmaker defined it. The next digit is the subsystem, like 3 for ignition and misfires or 4 for emissions.
A code isn’t a diagnosis
A code tells us which system noticed a problem. It doesn’t say which part failed. A lean code can be a vacuum leak, a dirty sensor or a weak fuel pump, so our $75 diagnostic tests before anyone buys parts. It comes off the repair if we do the work.
Flashing light?
A flashing check engine light means an active misfire. Drive as little as possible and text us.
Code list
74 common codes, explained
| Code | What it means | Drive? |
|---|---|---|
| P0010 | The computer sees a problem in the circuit that controls intake cam timing. | Book soon |
| P0011 | Intake cam timing isn't where the computer told it to be. | Book soon |
| P0014 | Exhaust cam timing isn't where the computer told it to be. | Book soon |
| P0016 | The crank and cam sensors disagree about engine timing. | Book soon |
| P0087 | The fuel system can't hold the pressure the engine needs. | Book soon |
| P0101 | The airflow sensor's reading doesn't match how the engine is running. | OK to drive |
| P0102 | The airflow sensor signal is lower than it should be. | OK to drive |
| P0113 | The intake air temperature sensor reads open or out of range high. | OK to drive |
| P0117 | The coolant temperature signal is shorted low, so the computer thinks the engine is extremely hot. | Book soon |
| P0118 | The coolant temperature signal is open or high, so the computer thinks the engine is very cold. | Book soon |
| P0122 | The throttle position signal is lower than possible. | Book soon |
| P0128 | The engine takes too long to warm up, usually because the thermostat is stuck open. | OK to drive |
| P0130 | The upstream oxygen sensor's signal isn't behaving right. | OK to drive |
| P0133 | The upstream oxygen sensor reacts too slowly. | OK to drive |
| P0135 | The heater inside the upstream oxygen sensor isn't working. | OK to drive |
| P0141 | The heater inside the downstream oxygen sensor, after the catalytic converter, isn't working. | OK to drive |
| P0171 | The engine is getting too much air or not enough fuel on bank 1. | Book soon |
| P0172 | The engine is getting too much fuel or not enough air on bank 1. | Book soon |
| P0174 | The engine is getting too much air or not enough fuel on bank 2. | Book soon |
| P0175 | The engine is getting too much fuel or not enough air on bank 2. | Book soon |
| P0217 | The engine has overheated. | Stop driving |
| P0299 | The turbo isn't making the boost the computer expects. | Book soon |
| P0300 | More than one cylinder is misfiring, or the misfire moves around. | Book soon |
| P0301 | Cylinder 1 is misfiring. | Book soon |
| P0302 | Cylinder 2 is misfiring. | Book soon |
| P0303 | Cylinder 3 is misfiring. | Book soon |
| P0304 | Cylinder 4 is misfiring. | Book soon |
| P0305 | Cylinder 5 is misfiring. | Book soon |
| P0306 | Cylinder 6 is misfiring. | Book soon |
| P0307 | Cylinder 7 is misfiring. | Book soon |
| P0308 | Cylinder 8 is misfiring. | Book soon |
| P0309 | Cylinder 9 is misfiring. | Book soon |
| P0310 | Cylinder 10 is misfiring. | Book soon |
| P0311 | Cylinder 11 is misfiring. | Book soon |
| P0312 | Cylinder 12 is misfiring. | Book soon |
| P0325 | The computer sees a problem in the knock sensor circuit. | OK to drive |
| P0335 | The computer isn't getting a good signal from the crankshaft position sensor. | Stop driving |
| P0340 | The computer isn't getting a good signal from the cam position sensor. | Book soon |
| P0401 | Not enough exhaust gas is flowing through the EGR system. | OK to drive |
| P0402 | Too much exhaust gas is flowing back into the intake. | Book soon |
| P0411 | The secondary air system, used at cold start, isn't moving enough air. | OK to drive |
| P0420 | The catalytic converter on bank 1 isn't cleaning the exhaust as well as it should. | OK to drive |
| P0430 | The catalytic converter on bank 2 isn't cleaning the exhaust as well as it should. | OK to drive |
| P0440 | A general fault in the fuel vapor (EVAP) system. | OK to drive |
| P0441 | The EVAP system isn't purging fuel vapor the way it should. | OK to drive |
| P0442 | A small leak in the fuel vapor system. | OK to drive |
| P0446 | A problem with the valve that vents the fuel vapor system. | OK to drive |
| P0455 | A large leak in the fuel vapor system. | OK to drive |
| P0456 | A very small leak in the fuel vapor system. | OK to drive |
| P0457 | The computer thinks the gas cap is loose or missing. | OK to drive |
| P0496 | Fuel vapor is being purged when it shouldn't be. | OK to drive |
| P0500 | The computer isn't getting a vehicle speed signal. | Book soon |
| P0505 | The idle control system can't hold the target idle speed. | OK to drive |
| P0506 | The idle is lower than the computer wants. | OK to drive |
| P0507 | The idle is higher than the computer wants. | OK to drive |
| P0521 | The oil pressure reading doesn't make sense. | Stop driving |
| P0562 | The computer sees low system voltage. | Book soon |
| P0563 | The computer sees system voltage that's too high. | Book soon |
| P0571 | The brake pedal switch signal is out of range. | Book soon |
| P0600 | Control modules are having trouble talking to each other. | Book soon |
| P0606 | The engine computer has detected an internal fault. | Book soon |
| P0700 | The transmission computer stored its own fault and asked for the check engine light. | Book soon |
| P0715 | The transmission input speed signal is missing or wrong. | Book soon |
| P0720 | The transmission output speed signal is missing or wrong. | Book soon |
| P0730 | The transmission is slipping or isn't in the gear it should be. | Stop driving |
| P0740 | The torque converter lockup circuit has a fault. | Book soon |
| P0741 | The torque converter isn't locking up when it should. | Book soon |
| P0750 | A transmission shift solenoid has a fault. | Book soon |
| P2096 | The sensor after the converter sees a lean mixture. | OK to drive |
| P2097 | The sensor after the converter sees a rich mixture. | OK to drive |
| P2135 | The two throttle position signals disagree. | Stop driving |
| P2187 | The engine runs lean at idle on bank 1. | OK to drive |
| P2195 | The upstream oxygen sensor reads lean and stays there. | OK to drive |
| U0100 | Other modules can't talk to the engine computer. | Stop driving |
Text us what the car is doing. We’ll send a price.
507-366-8902Call or text · Blaine, MN · 24/7
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