P0203: Injector Circuit/Open – Cylinder 3
Key takeaways
- P0203 is an electrical code: the engine computer can't drive the cylinder 3 fuel injector properly, so that cylinder usually misfires.
- Drive only short, gentle trips; if the check engine light flashes or you smell raw fuel, stop.
- Check the injector connector and wiring first ($100–$250); a new injector costs $250–$600.
- 7 complaints filed with NHTSA mention P0203; it is a code owners rarely quote.
- 66 manufacturer bulletins name P0203, and most of them send the technician to the injector wiring harness before the injector.
What P0203 means
The engine computer can’t operate the fuel injector for cylinder 3 the way it should. Scanners call it Injector Circuit/Open – Cylinder 3. The computer fires each injector by switching its circuit, and it watches the voltage on that circuit while it does. When what it sees doesn’t match what it commands, most often because the circuit is open, it sets P0203.
It’s a circuit code, not a clogged-injector code. Something between the computer and the injector’s coil isn’t carrying current. That can be the injector itself, but the connector and the wire come first.
Is it safe to drive?
Short trips only. Without a signal, the cylinder 3 injector usually stays shut, the cylinder misfires, and you get a rough idle, less power and often misfire code P0303. With a steady light, drive gently to a shop. Stop and have the car towed if the check engine light flashes, the engine stalls, or you smell raw fuel, which can mean the injector is stuck open instead of dead.
Causes, ranked
| Cause | How you confirm it | Typical cost (US independent shop, 2026) |
|---|---|---|
| Loose, unplugged or corroded injector connector | Look at the cylinder 3 injector plug; common right after intake, plug or coil work | $100–$250 (sometimes just a reseat) |
| Damaged injector wiring | Chafed, heat-damaged or chewed harness; test for power at the plug and continuity back to the computer | $100–$250 |
| Failed injector (open coil) | Injector resistance out of spec; on port injection, swap with a neighbor and the code moves | $250–$600 for one injector |
| Lost power feed to the injectors | Blown fuse or bad relay; several injector codes at once | $100–$250 |
| Software fault | Shop finds a matching bulletin for your engine | $100–$200; often $0 under a bulletin |
| Engine computer injector driver failed | Wiring and injector test good, but the computer’s output is dead | $800–$1,800 plus programming |
What to check first
- Read all the codes. P0203 alone points to cylinder 3’s own circuit. Several injector codes, or P0200, point to a shared fuse, relay or harness.
- Inspect the connector. Unplug it, check for corrosion, bent pins and a broken lock, and reseat it firmly.
- Check power at the plug with a test light, key on. No power means a fuse or feed wire.
- Measure the injector’s resistance against your engine’s spec.
- Swap injectors on a port-injected engine to see if the code follows. On direct injection, leave it to a shop; those injectors run on high voltage and high fuel pressure.
The bulletins point at wiring. GM’s for the 2021–2022 Escalade, Silverado 1500, Sierra 1500, Suburban and Yukon XL replace the injector together with the wiring harness. Volkswagen has an injector harness inspection for 2018–2020 Beetle, Passat and Tiguan models, and Ram tells technicians on some 2007–2009 trucks to check the injector wiring under the valve cover before replacing injectors. Two of the seven NHTSA complaints are from 2018 Tiguan owners, a model that VW harness bulletin covers.
What it costs
The cheap outcome is a connector or wire repair, $100–$250. The common outcome is one fuel injector, $250–$600, with direct-injection engines at the top. The expensive outcome is an engine computer, $800–$1,800 plus programming, which is rare and should only follow a full circuit test. An hour of diagnosis, usually $100–$180, costs less than buying an injector for a broken wire. If you want to go over your codes first, ask our AI mechanic.
Related codes
P0203 usually sets with P0303 and sometimes P0300. With P0202 it matches a Mazda bulletin pattern; with P0201 and P0204 as well, suspect the shared power feed. If the engine stumbles or bucks, see car sputtering and car jerks when accelerating.
What owners report to NHTSA
7 complaints filed with NHTSA mention P0203, 6 of them since 2015, across 6 different models. The component owners most often filed it under: electrical system.
Manufacturer service bulletins that name P0203
66 technical service bulletins and manufacturer communications filed with NHTSA mention P0203, from 12 makes. A bulletin means the manufacturer has documented a known cause or a fix procedure for that model. Examples:
- GMC SIERRA 1500 (2023, 2024), bulletin 11001835: This engineering information (EI) is requesting information from technicians to perform the check list provided and contact the engineer listed in regards the Check Engine Lamp illuminated on Driver Information Center (D…
- CHEVROLET SUBURBAN (2024, 2023), bulletin 11001835: This engineering information (EI) is requesting information from technicians to perform the check list provided and contact the engineer listed in regards the Check Engine Lamp illuminated on Driver Information Center (D…
- CADILLAC ESCALADE ESV (2023, 2024), bulletin 11001835: This engineering information (EI) is requesting information from technicians to perform the check list provided and contact the engineer listed in regards the Check Engine Lamp illuminated on Driver Information Center (D…
- CHEVROLET TAHOE (2023, 2024), bulletin 11002311: This engineering information (EI) is requesting information from technicians to perform the check list provided and contact the engineer listed in regards the Check Engine Lamp illuminated on Driver Information Center (D…
- GMC YUKON (2023, 2024), bulletin 11002311: This engineering information (EI) is requesting information from technicians to perform the check list provided and contact the engineer listed in regards the Check Engine Lamp illuminated on Driver Information Center (D…
- CADILLAC ESCALADE (2023, 2024), bulletin 11002311: This engineering information (EI) is requesting information from technicians to perform the check list provided and contact the engineer listed in regards the Check Engine Lamp illuminated on Driver Information Center (D…
Sources: NHTSA Office of Defects Investigation complaint database and manufacturer communications file, snapshots September 2026. A complaint or bulletin that mentions a code is a report about that vehicle, not a statement that the code has one cause.
Frequently asked questions
Does P0203 mean the injector is bad?
Not necessarily. P0203 means the computer sees a problem in the injector's electrical circuit. A loose connector, a corroded pin or a damaged wire sets the same code, so test those before buying an injector.
Can I drive with P0203?
Short, gentle trips to a shop are usually fine if the light is steady. Cylinder 3 is probably not getting fuel, so the engine runs rough. A flashing light, a strong fuel smell or stalling means stop.
Why do P0202 and P0203 show up together?
Look for something the two circuits share, such as a harness section or connector. Mazda has a bulletin for this exact pairing on the 2013–2017 Mazda3, CX-5 and Mazda6, and GM gathered technician reports on the same pair for 2023–2024 full-size trucks and SUVs.
Where is cylinder 3?
It depends on the engine. On most inline four-cylinders it's the third from the timing end. On V engines each maker numbers cylinders its own way, so look it up before unplugging anything.