Symptom
Check engine light illuminated
The malfunction indicator lamp is on steadily. A steady lamp means a fault is stored and should be investigated, but not that the car must stop immediately — that is what a flashing lamp means.
Also described as: cel, mil, engine light, check engine light, engine management light, eml, warning light, orange engine light, yellow engine light, چراغ چک روشن شد, چراغ چک, چراغ موتور روشن شد, چک انجین, luz check engine, testigo motor encendido, luz motor encendida, check engine prendido, luz amarilla motor, لمبة المحرك مضيئة, علامة المحرك ظهرت, تشيك انجن, لمبة الفحص اشتغلت, إشارة المحرك الصفراء
Some causes mean you should stop driving
139 of the 2,552 codes that produce this symptom indicate a fault where continuing to drive risks damage or is unsafe. If the symptom is sudden or severe, treat it as one of those until a scan says otherwise.
What this usually means
The lamp says a fault is stored. It does not say which, how serious, or whether the car is safe — and that is not a shortcoming, it is the whole design. One lamp stands in for every fault the engine management can detect, from a fuel cap that is not sealing to a misfire eating the catalyst. Reading it as a severity signal is the mistake almost everybody makes, in both directions: some people stop on the hard shoulder for a loose filler cap, and some drive for months on a fault that is quietly destroying something.
What the lamp does discriminate is steady against flashing, and that distinction is real and standardised. Steady means a fault is stored and should be investigated. Flashing means an active misfire severe enough to damage the catalytic converter, and that one genuinely means stop as soon as it is safe rather than book it in.
A steady lamp that goes out on its own has not fixed itself. The management extinguishes it after a number of consecutive fault-free driving cycles and keeps the fault as history, so the evidence is still there for a scan tool and the underlying condition may simply not have recurred yet. Clearing a code without reading it first is worse, because it destroys the freeze-frame data — the snapshot of what the engine was doing at the moment the fault set — which is very often the only record of an intermittent fault anybody will get. It also resets the readiness monitors, so a car cleared on the way to an emissions test fails it for being untestable.
The honest next step is a code, and then a page. That is what this corpus exists for: the number narrows a whole car to one subsystem, and the page for that number says what it means, what typically causes it, and whether it is safe to keep driving. A steady lamp with a code in hand is a small job. A steady lamp ignored for six months is how a sensor fault becomes a catalytic converter.
Working through it
| What you find | Likely cause | How to confirm it | What fixes it |
|---|---|---|---|
| Steady lamp, car drives exactly as it always has | A stored fault the management has not needed to act on — the largest group by far, and the one where the code is everything | Read the code and its freeze-frame data before clearing anything. Note the code number: that is what turns a whole-car problem into a one-page one. | Diagnose the specific code on its own page. Driving on is usually acceptable in the short term, but the lamp is not going to tell you when that stops being true. |
| Lamp flashing rather than steady | Active misfire severe enough to put raw fuel into the catalyst | No confirmation needed at the roadside — flashing is itself the finding. Reduce load and stop as soon as it is safe. | Do not continue driving to see if it settles. Diagnose the misfire before the catalyst is damaged, which happens in minutes rather than weeks. |
| Steady lamp with reduced power or a limp-mode message | The management has not just recorded the fault, it has acted on it — protection or a signal it no longer trusts | Read codes and check whether an ignition cycle restores power. A limit that returns after restart is imposed rather than mechanical. | Treat as more urgent than a steady lamp alone. The car is telling you it is protecting something. |
| Came on within a drive or two of refuelling | Evaporative emission system — very often the filler cap not sealing, sometimes the cap's seal rather than the cap | Check the cap is the right one, is undamaged, and clicks home. Read the code: the evaporative family is distinctive and will name itself. | Reseat or renew the cap, then allow several drive cycles for the lamp to extinguish. Do not clear it just to see. |
| Lamp went out by itself and nothing was done | The fault has not recurred for enough consecutive drive cycles — it is stored as history, not repaired | Scan for history and pending codes, not just current ones. An intermittent that clears is the commonest reason a car arrives with a complaint and a clean dashboard. | Read the stored history and its freeze frame. If it names a real fault, treat it as real — it will be back. |
| Lamp on, but a basic reader finds no codes | The fault is in a module the reader is not talking to — the lamp can be requested by more than the engine management | Scan every module rather than the powertrain alone. A cheap reader that only sees generic powertrain codes reports a clean car that plainly is not. | Use a tool that reads all modules, or have it scanned properly. Do not conclude the lamp is faulty. |
| The code was cleared before anyone read it | The freeze-frame evidence is gone and the readiness monitors have reset | Nothing to confirm — the record is destroyed. Drive the car until the fault returns and read it properly next time. | Complete the drive cycles before any emissions test, or the car fails for incomplete monitors regardless of whether it is healthy. |
| Lamp on alongside oil pressure, temperature or brake warnings | Two different systems reporting, and the other lamp is the one that matters | Read the other warning first. Oil pressure and coolant temperature are engine-destroying in minutes; a stored emissions fault is not. | Act on the more urgent lamp immediately, then diagnose the stored fault afterwards. |
-
Steady lamp, car drives exactly as it always has
- Likely cause
- A stored fault the management has not needed to act on — the largest group by far, and the one where the code is everything
- How to confirm it
- Read the code and its freeze-frame data before clearing anything. Note the code number: that is what turns a whole-car problem into a one-page one.
- What fixes it
- Diagnose the specific code on its own page. Driving on is usually acceptable in the short term, but the lamp is not going to tell you when that stops being true.
-
Lamp flashing rather than steady
- Likely cause
- Active misfire severe enough to put raw fuel into the catalyst
- How to confirm it
- No confirmation needed at the roadside — flashing is itself the finding. Reduce load and stop as soon as it is safe.
- What fixes it
- Do not continue driving to see if it settles. Diagnose the misfire before the catalyst is damaged, which happens in minutes rather than weeks.
-
Steady lamp with reduced power or a limp-mode message
- Likely cause
- The management has not just recorded the fault, it has acted on it — protection or a signal it no longer trusts
- How to confirm it
- Read codes and check whether an ignition cycle restores power. A limit that returns after restart is imposed rather than mechanical.
- What fixes it
- Treat as more urgent than a steady lamp alone. The car is telling you it is protecting something.
-
Came on within a drive or two of refuelling
- Likely cause
- Evaporative emission system — very often the filler cap not sealing, sometimes the cap's seal rather than the cap
- How to confirm it
- Check the cap is the right one, is undamaged, and clicks home. Read the code: the evaporative family is distinctive and will name itself.
- What fixes it
- Reseat or renew the cap, then allow several drive cycles for the lamp to extinguish. Do not clear it just to see.
-
Lamp went out by itself and nothing was done
- Likely cause
- The fault has not recurred for enough consecutive drive cycles — it is stored as history, not repaired
- How to confirm it
- Scan for history and pending codes, not just current ones. An intermittent that clears is the commonest reason a car arrives with a complaint and a clean dashboard.
- What fixes it
- Read the stored history and its freeze frame. If it names a real fault, treat it as real — it will be back.
-
Lamp on, but a basic reader finds no codes
- Likely cause
- The fault is in a module the reader is not talking to — the lamp can be requested by more than the engine management
- How to confirm it
- Scan every module rather than the powertrain alone. A cheap reader that only sees generic powertrain codes reports a clean car that plainly is not.
- What fixes it
- Use a tool that reads all modules, or have it scanned properly. Do not conclude the lamp is faulty.
-
The code was cleared before anyone read it
- Likely cause
- The freeze-frame evidence is gone and the readiness monitors have reset
- How to confirm it
- Nothing to confirm — the record is destroyed. Drive the car until the fault returns and read it properly next time.
- What fixes it
- Complete the drive cycles before any emissions test, or the car fails for incomplete monitors regardless of whether it is healthy.
-
Lamp on alongside oil pressure, temperature or brake warnings
- Likely cause
- Two different systems reporting, and the other lamp is the one that matters
- How to confirm it
- Read the other warning first. Oil pressure and coolant temperature are engine-destroying in minutes; a stored emissions fault is not.
- What fixes it
- Act on the more urgent lamp immediately, then diagnose the stored fault afterwards.
Codes that produce this symptom (2,552)
Listed with the codes that most typically present this way first — the likeliest place to start.
- C0604 Active Air Dam Control Circuit Performance Typical of this code Low
- P0001 Fuel Volume Regulator A Control Circuit/Open Typical of this code Stop driving High
- P0002 Fuel Volume Regulator A Control Circuit Range/Performance Typical of this code Stop driving High
- P0003 Fuel Volume Regulator A Control Circuit Low Typical of this code Stop driving High
- P0004 Fuel Volume Regulator A Control Circuit High Typical of this code Stop driving High
- P0005 Fuel Shutoff Valve A Control Circuit/Open Typical of this code Stop driving High
- P0006 Fuel Shutoff Valve A Control Circuit Low Typical of this code Stop driving High
- P0007 Fuel Shutoff Valve A Control Circuit High Typical of this code Stop driving High
- P000A A Camshaft Position Slow Response Bank 1 Typical of this code Moderate
- P000B B Camshaft Position Slow Response Bank 1 Typical of this code Moderate
- P000C A Camshaft Position Slow Response Bank 2 Typical of this code Moderate
- P000D B Camshaft Position Slow Response Bank 2 Typical of this code Moderate
- P0010 A Camshaft Position Actuator A Control Circuit/Open Bank 1 Typical of this code Moderate
- P0013 B Camshaft Position Actuator A Control Circuit/Open Bank 1 Typical of this code Moderate
- P0020 A Camshaft Position Actuator A Control Circuit/Open Bank 2 Typical of this code Moderate
- P0023 B Camshaft Position Actuator A Control Circuit/Open Bank 2 Typical of this code Moderate
- P0026 Intake Valve Control Solenoid Circuit Range/Performance — Bank 1 Typical of this code Moderate
- P0027 Exhaust Valve Control Solenoid Circuit Range/Performance — Bank 1 Typical of this code Moderate
- P0028 Intake Valve Control Solenoid Circuit Range/Performance — Bank 2 Typical of this code Moderate
- P0029 Exhaust Valve Control Solenoid Circuit Range/Performance — Bank 2 Typical of this code Moderate
- P0030 O2 Sensor Heater Control Circuit — Bank 1 Sensor 1 Typical of this code Moderate
- P0031 O2 Sensor Heater Control Circuit Low — Bank 1 Sensor 1 Typical of this code Moderate
- P0032 O2 Sensor Heater Control Circuit High — Bank 1 Sensor 1 Typical of this code Moderate
- P0033 Turbocharger/Supercharger Bypass Valve A Control Circuit Typical of this code Moderate
- P0034 Turbocharger/Supercharger Bypass Valve A Control Circuit Low Typical of this code Moderate
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
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