P0202
- Powertrain
- Generic (SAE)
- Emissions
Get it looked at now
An unfuelled cylinder misfires continuously, and the oxygen it pumps into the exhaust drives the remaining cylinders rich into an oxygen-loaded converter, which can overheat and be destroyed. A flashing check engine light means that damage is happening now. A short to ground can also take out the module's injector driver.
- Safe to drive
- Get it to a shop with minimal driving. If the check engine light is flashing, pull over and arrange a tow.
Injector Circuit Malfunction — Cylinder 2
The computer found a fault in the cylinder 2 injector circuit — most commonly an open: an open winding, or a break in the feed or control wire. Depending on the fault and the vehicle, the module may also shut that injector's driver down to protect its output stage, in which case cylinder 2 gets no fuel. Confirm whether the cylinder is actually dead — misfire counters, a stored P0302, or a current ramp — rather than assuming it.
Same mechanism as the other injector circuit codes, applied to the cylinder 2 driver. The module switches the injector's ground side and evaluates current flow, flagging open loads, shorts to ground and shorts to supply. P0202 is defined as Injector Circuit/Open for cylinder 2, and on most vehicles an open load is what sets it; a short to ground or to supply usually sets P0264 or P0265 instead. Some manufacturers do use P0202 for any cylinder 2 injector circuit fault, so read what else is stored before assuming which condition occurred. One detail matters more here than it does on cylinder 1: on a V-configuration engine, cylinder 2 may sit on the opposite bank from cylinder 1 or immediately beside it, depending entirely on the manufacturer's numbering convention. That determines which harness branch, which connector run and which module driver bank you should be testing.
How the car detected itEach injector driver carries its own diagnostic. The module energises the cylinder 2 driver and evaluates current: none when commanded means an open circuit, current when not commanded means a short to ground, and excessive current means a shorted winding or a short to supply. Because it is trapped on the electrical side rather than inferred over time, the code sets quickly — often within the same key cycle. Many modules then disable the driver to protect the output stage, which is why the cylinder can go dead as soon as the code sets; others log the fault and keep commanding the injector, so verify the cylinder's contribution before assuming it is out.
A trouble code records what a control module measured. It does not identify which part failed. Test before replacing anything.
- Safe to drive
- Get it to a shop with minimal driving. If the check engine light is flashing, pull over and arrange a tow.
- Urgency
- Get it looked at now
- Will it pass emissions
- No
- If ignored
- The engine keeps running rough with a dead cylinder, loses power and burns more fuel. The unfuelled cylinder pumps raw air into the exhaust, which skews that bank's fuel trims and drives excess fuel from the remaining cylinders into a converter already full of oxygen — that combination overheats and can ruin it, a repair often several times the cost of an injector. If the injector is firing intermittently rather than not at all, raw fuel goes down the pipe as well, which is worse. Those skewed trims also frequently trigger lean codes for the bank, which sends the next person to look at the car chasing a vacuum leak that does not exist. If the underlying fault is a short to ground, the module's driver can be permanently damaged. A flashing light means that damage is happening as you drive.
- Check engine light
- Solid
- Clearing the light
- A completed drive cycle is normally required before the monitor re-runs and the light can clear.
These are the causes this code can have. For the order to work through them in, see what to check first.
| # | Cause | How often | Component |
|---|---|---|---|
| 1 | Injector winding failed open | Very common | — |
| 2 | Wiring or connector fault | Common | — |
Ordering reflects how often each cause is responsible in general, not a probability for your vehicle. Confirm by testing.
In order. Each of these is cheaper or faster than what follows it, and each one can make the rest unnecessary.
Whether P0302 (cylinder 2 misfire) is stored alongside it
Confirms the cylinder is actually dead, which tells you the fault is present now rather than intermittent and makes live testing worthwhile.
Whether other injector circuit codes are stored at the same time
Two or more injector codes almost always mean a shared feed, ground, connector or module driver bank — not two injectors failing together. That changes where you start entirely.
Which physical cylinder is number 2, and which bank it belongs to
Numbering conventions differ, and on many V engines cylinder 2 is on the opposite bank from cylinder 1. This decides which harness branch to test.
The injector connector for oil intrusion, corrosion or loose terminals
The most common repairable cause on this code, and inspecting it costs nothing.
Harness routing near heat sources, brackets and the valve cover
Chafe and heat damage are cheap to repair and easy to miss — and they will kill a new injector too if left alone.
Read all stored codes and read the pattern before touching anything
Tools Scan tool
A single injector circuit code isolates the fault to that one branch. Several at once redirects the whole diagnosis toward the shared power feed, ground, relay or module driver bank. Note any misfire or bank-level lean codes as supporting evidence.
ExpectedA clear picture of whether this is a single-circuit fault or part of a group failure.
Identify cylinder 2's physical location and bank
Tools Vehicle service information
Confirm against the manufacturer's own numbering and firing order. Do not assume cylinder 2 sits next to cylinder 1 — on many V engines it is on the opposite bank, which changes which harness you open.
ExpectedPosition and bank confirmed, along with which module driver bank serves that cylinder.
Inspect the connector and check terminal tension
Tools Hand tools, terminal test probe, bright light
Unplug and look for oil, coolant, corrosion, melted plastic and heat damage. Test terminal grip with a matching probe rather than judging by eye. A loose terminal produces exactly this code intermittently and passes every static test.
ExpectedClean, dry terminals with firm tension and an intact connector seal.
Measure the injector's coil resistance and compare it against every other injector
Tools Digital multimeter
Measure at the injector itself. Relative comparison across the set is a valid test even without a published specification, which is important because that value is vehicle-specific and differs sharply between port, direct-injection and diesel designs.
ExpectedConsistent readings across the set. An open circuit, or a value well outside the group, identifies the injector.
Verify power and control at the connector
Tools Multimeter, noid light or oscilloscope, low-current probe, wiring diagram
Confirm battery voltage on the feed side where the design uses one, and check for a switching pulse on the control side while cranking. Do not backprobe direct-injection or piezo diesel circuits with the system live — those run from a boosted supply, roughly 60-70 volts on GDI solenoid systems and 100-200 volts on piezo diesels. Treat it as a shock hazard, keep a test light or an unprotected scope input off it, and use a low-current clamp around the wire instead.
ExpectedCorrect feed voltage and a regular control pulse matching the other injectors.
Current-ramp the injector during cranking or idle
Tools Low-current probe and oscilloscope
The current waveform shows whether the injector is conducting normally and whether the pintle is actually moving. Compare the trace directly against a known-good cylinder on the same engine.
ExpectedA clean current ramp with a visible pintle bump, matching the other injectors in shape and amplitude.
Voltage-drop and wiggle test the feed and control circuits back toward the module
Tools Multimeter, scan tool with recording
Measure drop across the feed and control paths while the injector is actually being commanded — a continuity check passes a corroded joint that collapses under load. Then move the harness through its range with data recording running, concentrating where the loom passes brackets, the valve cover and heat sources. This costs nothing and comes before anything that requires removing the rail.
ExpectedMinimal voltage drop and no change during the wiggle test. Any change localises the fault to that harness run.
Swap the injector with a neighbouring cylinder's and re-test
Tools Hand tools, new seals and O-rings, seal sizing tool where required, scan tool with injector coding
Only once the feed and control circuits have tested clean under load does the swap become the remaining test. Fit new seals when you do it. On GDI and common-rail diesel engines, injectors carry calibration codes tied to a cylinder — update those codes in the module when you move them, or the swap creates its own fault and the result is meaningless. GDI Teflon combustion seals are single-use and require a sizing tool; diesel injectors need new copper washers and the specified clamp torque. If that tooling or coding capability is not available, prove the circuit electrically instead of swapping. Then clear codes, run the engine and see which cylinder the code reports against.
ExpectedThe code follows the injector if the injector is faulty, and stays with cylinder 2 if the wiring or module driver is.
Recheck fuel trims and misfire counters after the repair
Tools Scan tool with live data
A dead cylinder skews that bank's trims, so verifying they return to normal confirms both the repair and that no secondary fault was hiding behind the injector code.
ExpectedThat bank's trims back within roughly plus or minus 10 percent, and the cylinder 2 misfire counter staying at zero through a full drive cycle.
| Repair | Only after you confirm | Typical cost | Who |
|---|---|---|---|
| Repair or replace the injector connector and terminals | Contamination, corrosion or lost terminal tension found, with the injector coil measuring normal. | $100–$350 | DIY |
| Repair the shared injector power feed, fuse or relay | Several injector circuits failing together, with the feed measuring low or absent at the injectors with the key on. | $80–$350 | DIY |
| Replace injector seals and O-rings | Required whenever the injector is removed, or hardened and damaged seals found on inspection. | $30–$220 | DIY |
| Replace the cylinder 2 fuel injector | Coil measures open or well outside the range of its neighbours, or the code follows the injector when swapped to another cylinder. | $150–$900 | DIY |
| Repair a chafed, broken or heat-damaged injector harness wire | Voltage drop under load, an open circuit, or a wiggle-test change isolating the fault to a section of harness rather than the injector. | $120–$450 | Hard |
| Repair a short to ground or to supply in the injector control circuit | Current flowing with the driver commanded off, or supply voltage present on the control wire with the injector unplugged. Note that on most vehicles these conditions set P0264 or P0265 rather than P0202. | $150–$600 | Hard |
| Repair or replace the engine control module | Injector, connector and wiring all verified good, but the driver still fails to switch the circuit. | $600–$1,800 | Shop |
US independent-shop ranges, parts and labour, excluding diagnostic time. Cylinder 2 on the rear bank of a transverse V engine can require intake manifold removal, which adds hours of labour and pushes the job toward the top of every range.
- Treating two or more injector circuit codes as two failed injectors. Look for the shared feed, ground or driver bank first.
- Assuming cylinder 2 sits next to cylinder 1. On many V engines it is on the opposite bank.
- Fitting a new injector without curing the oil-soaked connector that killed the last one.
- Chasing the bank-level lean code that a dead cylinder caused instead of the injector fault that caused the lean code.
- Backprobing a live direct-injection or piezo injector circuit. The boosted drive voltage is a shock hazard and will damage a test light or an unprotected scope input — measure it with a current clamp.
- Pulling the rail for a swap test before voltage-drop and wiggle testing the circuit, which is free and finds the harness faults.
- Moving a GDI or common-rail diesel injector to another cylinder without transferring its calibration code in the module, which creates a fresh fault and makes the swap test meaningless.
- Skipping new seals and O-rings when the injector comes out.
- Clearing the code and delivering the car without a road test that confirms the misfire counter stays at zero.
- Fuel Injector
- Injector Wiring
- Definition
- Generic code set (SAE J2012 / ISO 15031-6) via the OBDexopen database, dedicated to the public domain under CC0-1.0.
- Diagnostic guidance
- Written and reviewed in-house. See our editorial policy.
- Review status
- Reviewed
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