Four injector codes at once? Probably not four injectors

P0201, P0202, P0203 and P0204 are the injector circuit codes for cylinders one through four. Get a scan back with two or three of them at once and the instinct is to start pricing a full set of injectors. Our data says that instinct is usually wrong.

What the codes actually mean

Each of these codes covers one cylinder's injector driver circuit — the ECU commands the injector to open by pulsing a ground or a power feed, and the code sets when that circuit does not behave the way the driver expects: no current draw, a short, or an open. Critically, the code is about the *circuit*, not about whether fuel actually left the injector tip. A perfectly good injector reports the identical fault if the wire feeding it, the connector it plugs into, or the driver inside the ECU that switches it, is the part that failed.

What the telemetry says

This is where the shared-circuit theory stops being a guess:

Two-thirds of P0201 scans also carry P0202, and nearly two-thirds also carry P0203. Run the comparison the other way and it holds just as well — P0202 and P0203 show up together 70.4%/70.0% of the time. Four separate cylinders do not fail their individual injectors in lockstep that reliably. What does fail that reliably is a shared power feed to the injector bank, a common ground point, a connector at the engine harness junction, or — on some platforms — the ECU's own injector driver stage for that bank. One bad connection produces two, three or four codes depending on how many cylinders share that connection.

P2263 — turbocharger boost system performance — rides along on a fifth to a third of these scans. It is not part of the injector circuit and it is not caused by it; a lean or rich condition from misbehaving injectors can be enough to throw the boost control's own targets off, which is a plausible secondary effect worth knowing about rather than a separate problem to chase.

The cheap-versus-expensive fork

This is the practical reason the distinction matters. A connector repair, a chafed harness section, or a corroded ground point is a parts cost measured in nothing much and a job measured in an hour. Four injectors is a different order of expense entirely. The data gives you a reason to check the cheap explanation first: if three or four of these codes are present together, go looking for one shared point of failure before you assume you are looking at four failed parts.

One make is worth knowing about here

Renault accounts for roughly 36% of scans carrying each of these four codes — 8.5x its 4.2% share of the fleet we see overall — with the Duster making up 21–33% of the vehicles we could identify on each code. There is a Renault-specific code worth checking alongside them: P1525 (2,056 scans in our data), which co-occurs with P2263 at 61.0% and with P0201 at 59.0%, and is 77.4% Duster among vehicles we could identify. It does not have a public code-lookup page, so treat it as a signal to scan for rather than a code to look up on its own — but if you are working on a Renault and see it, the injector-and-boost cluster above is exactly where to keep looking.

What to do next

Pull the injector harness connector at the engine and check it before anything else — corrosion or a loose pin there is the single most common cause of a multi-cylinder injector code cluster. If that looks clean, check the injector power feed fuse and the shared ground point for that bank; a voltage drop test across the connector under cranking will show a bad connection faster than swapping parts will. Only after those check out clean does it make sense to test the injectors themselves individually, with a resistance check or a noid light, one cylinder at a time.

If only one of the four codes is present, this reasoning does not apply — a single injector code with no companions is more likely to be that one injector, and is worth treating as its own fault rather than assuming a shared cause that the data does not show.