P0203
Fix within a few daysCylinder 3 Fuel Injector Circuit Malfunction
Code P0203 means there's an electrical problem with cylinder 3's fuel injector circuit. Common causes: Faulty injector (50%), wiring issues (30%), bad PCM (10%). Drivability: Limit driving, fix within a few days. Repair cost: $60-$200 DIY, $250-$600 professional.
Can I Drive With P0203?
Limit driving, fix within a few days
Essential trips under 10 miles, avoid highways and heavy acceleration. Prioritize immediate repair.
Stop driving immediately if: Flashing Check Engine Light, strong burning smell, significant power loss, or loud engine noises.
Symptoms of P0203
- 1Engine misfire or rough idle
- 2Reduced engine power
- 3Poor fuel economy
- 4Check Engine Light is on or flashing
- 5Engine may run rough or stall
Common Causes of P0203
Parts most likely causing this code, ranked by probability
The fuel injector for cylinder 3 has an internal electrical fault, such as an open circuit or short, preventing it from operating correctly.
50% of P0203 cases are fixed by replacing this part
Damaged, chafed, or corroded wiring in the circuit leading to the cylinder 3 fuel injector prevents proper electrical signal transmission.
30% of P0203 cases are fixed by repairing or replacing wiring
The driver circuit within the engine computer responsible for controlling the cylinder 3 injector has failed, which is a less common but serious issue.
10% of P0203 cases are fixed by replacing the ECM/PCM
A loose, corroded, or damaged electrical connector at the cylinder 3 fuel injector prevents a solid electrical connection.
10% of P0203 cases are fixed by repairing or replacing the connector
Check These First (Before Buying Parts)
- Visually inspect the wiring harness and connector for cylinder 3's fuel injector for any obvious damage, fraying, or corrosion.
- Ensure the fuel injector connector is securely seated on the injector.
How to Diagnose P0203
- 1Visually inspect the wiring harness and connector for cylinder 3's fuel injector for any signs of damage, corrosion, or loose connections.
- 2Using a multimeter, test the resistance of the cylinder 3 fuel injector and compare it to the resistance of a known good injector (e.g., cylinder 1 or 2).
- 3With the engine running, use a noid light or multimeter to check for power and ground signals at the cylinder 3 injector connector.
- 4If the injector resistance and wiring appear good, swap the cylinder 3 injector with an injector from another cylinder (if easily accessible) and see if the code moves to the new cylinder.
- 5If the code does not move after swapping injectors and wiring is confirmed good, test the injector driver circuit directly from the ECM/PCM connector.
P0203 on Popular Vehicles
Ford F-150
2004-2024Injector failures are common, particularly on EcoBoost engines. Wiring harness chafing near the intake manifold or fuel rail is also a known issue.
65% fixed by replacing injector or repairing wiring
Honda Civic
2006-2024While less frequent, P0203 on Civics often points to a failing injector or a corroded connector due to moisture intrusion. Inspect the connector pins carefully.
60% fixed by replacing injector or cleaning/repairing connector
Chevrolet Silverado
2007-2024On Silverado trucks, especially with V8 engines, P0203 can be due to a faulty injector or, less commonly, a damaged section of the engine wiring harness that runs over the valve covers.
60% fixed by replacing injector or repairing wiring
Frequently Asked Questions
What does P0203 mean?
P0203 indicates that the engine's computer has detected an electrical fault in the circuit that controls the fuel injector for cylinder number 3. This means the computer is not seeing the expected electrical signal from or to the injector.
Can I drive with P0203?
Limit driving. While your vehicle may still run, a P0203 code means cylinder 3 is misfiring. Continued driving with a misfire sends unburned fuel into your exhaust, which can quickly damage your catalytic converter, leading to a much more expensive repair.
Will P0203 clear itself?
No, P0203 will not clear itself. This code indicates a hard electrical fault that requires diagnosis and repair. The Check Engine Light will remain on until the underlying issue is fixed and the code is cleared, either manually with a scan tool or after several drive cycles once the fault is resolved.
How do I fix P0203 myself?
Start by visually inspecting the wiring and connector for cylinder 3's fuel injector. If no obvious damage, test the injector's resistance with a multimeter. If the injector is faulty, replace it. If the injector is good, test the wiring for continuity and power/ground signals. A new fuel injector is a common fix.
How much does it cost to fix P0203?
DIY repair costs for P0203 typically range from $60 to $200, mainly for a new fuel injector or wiring repair parts. Professional repair at a shop will cost between $250 and $600, covering parts and labor for diagnosis and replacement.
P0203 keeps coming back - why?
If P0203 keeps returning, it means the initial repair did not address the root cause. Common reasons for recurrence include: an intermittent wiring issue that was missed, a faulty connector not fully repaired, a new injector that was also defective, or a rare but possible issue with the Engine Control Module (ECM) itself.
Will P0203 fail emissions/smog test?
Yes, P0203 will cause your vehicle to fail an emissions or smog test. The Check Engine Light being on is an automatic failure in most states, and a misfire directly impacts exhaust emissions, making it impossible to pass.
What's the difference between P0203 and P0303?
P0203 specifically indicates an electrical circuit malfunction with the cylinder 3 fuel injector. P0303 indicates a general misfire detected in cylinder 3. A P0203 code will almost always trigger a P0303 code because the injector circuit fault causes the misfire. However, a P0303 can be caused by many other issues (spark, compression, etc.) without a P0203.
P0203 on Ford F-150 - what's common?
On Ford F-150s, especially with EcoBoost engines, P0203 is commonly caused by a faulty fuel injector itself. Wiring harness issues due to heat or vibration are also seen. Always start with a thorough visual inspection and electrical testing of the injector and its circuit.
Questions to Ask Your Mechanic
Did you test the resistance of the cylinder 3 injector and compare it to others?
Good answer: Yes, I measured it at X ohms, while the others were Y ohms, indicating an open circuit in cylinder 3. Or, all injectors measured within spec.
What did you find when checking for power and ground at the injector connector?
Good answer: I confirmed constant power and a pulsing ground signal with a noid light, so the PCM is trying to fire the injector. Or, I found no power/ground, indicating a wiring issue.
Repair Cost Estimate
DIY Repair
Parts only
$60-$200
Shop Repair
Parts + labor
$250-$600
Save $190-$400 by doing it yourself
Difficulty
intermediate
Time
1-3 hours
Intermediate - requires basic electrical testing skills and tools like a multimeter and noid light, along with the ability to safely remove and install a fuel injector.
Cost of Waiting
Ignoring P0203 and the resulting misfire will send unburned fuel into your catalytic converter. This causes the converter to overheat and melt internally, leading to a complete failure. A $60-$200 fuel injector repair now prevents a $800-$2,500 catalytic converter replacement later.
While You're In There...
These seals often degrade over time and are removed during injector replacement. Replacing them prevents fuel leaks and ensures a proper seal.
A misfire can foul the spark plug. Replacing it ensures optimal ignition once the injector issue is resolved, and it's often easily accessible during injector work.
Tools You'll Need
- OBD-II scan tool
- Multimeter
- Noid light set
- Basic hand tools (sockets, wrenches)
- Fuel injector puller (if applicable)
P0203 is a common electrical fault that is usually straightforward to diagnose and fix. Most repairs involve replacing a single component, and your engine will run smoothly again afterward.
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Your Next Steps
Step 1: Perform a thorough visual inspection of the cylinder 3 fuel injector's wiring and connector. Look for any cuts, chafing, or corrosion.
Step 2: Use a multimeter to test the resistance of the cylinder 3 fuel injector. Compare it to the resistance of a good injector from another cylinder. If it's out of spec, replace the injector.
Step 3: If the injector tests good, use a noid light to confirm the PCM is sending a pulse to the injector. If not, trace the wiring back to the PCM for opens or shorts. Parts you'll likely need: a new fuel injector, wiring repair kit, or a new injector connector.