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2003 Mitsubishi Eclipse P0202 Code: Misfire in Cylinder 2 - Injector or Circuit Issue?

Model: 2003 Mitsubishi Eclipse Fault Code: P0202 Posted: 2011-12-03 14:21

I have a 2003 Mitsubishi Eclipse with a 3.0L engine that is showing fault code P0202, indicating an issue with the fuel injector on cylinder 4. However, I recently replaced the injector and the problem persists. The car now exhibits a misfire, and I also see code P0302, which points to a misfire in cylinder 2. I tested the resistance of all three injectors (cylinders 2, 4, and 6) using an ohmmeter: cylinders 4 and 6 read between 3–6 ohms (within specification), but cylinder 2 reads only 1.0 to 1.5 ohms—significantly lower than the expected range of 3–6 ohms. I also confirmed that power (12V) is present at the injector terminals. I then used a noid light to test pulse activity: cylinders 4 and 6 responded with proper flashing, but cylinder 2 showed no pulse when tested. This suggests either an electrical circuit issue or a problem with the engine control module (ECM). I performed a continuity check on the wiring harness from the ECM to cylinder 2, and the path appears intact. However, I'm now unsure whether to proceed with further diagnostics or suspect a faulty ECM. Could this be a wiring fault in the injector circuit? Or is it possible that the P0202 code is actually related to an ignition system issue rather than a direct injector failure? Any guidance on how to properly diagnose and fix this would be greatly appreciated.

Related fault codes

P0202

Comments (9)

Anonymous 2011-12-03 18:00

Use a noid light to check for proper pulse signal at the injector. Code P0202 is typically not caused by a faulty injector but rather by an electrical circuit issue—such as poor wiring or a failing harness. The resistance of 1.5 ohms on cylinder 2 is unusually low; this could indicate a short or internal failure, but it's not definitive. Try swapping the injector from cylinder 4 or 6 (which have normal readings) into cylinder 2 and see if the code clears. This will help isolate whether the issue lies with the injector itself or the wiring/circuit.

Anonymous 2011-12-05 20:14

I tested the noid light on cylinders 4 and 6—both responded correctly. When I connected it to cylinder 2, there was no flash at all. This means the injector is not receiving a pulse signal from the ECU. Next step: perform a volt drop test along the wiring harness between the ECM and cylinder 2, or use an overlay harness to bypass the existing circuit and directly connect the PCM to the injector. If the noid light works with the overlay, the issue lies in the original wiring; if not, the problem may be with the ECM.

Anonymous 2011-12-06 06:08

Yes—verify the entire circuit path using a detailed wiring diagram and trace it from the PCM to the injector. Look for any open circuits or high resistance points that could prevent proper signal transmission.

Anonymous 2011-12-07 09:58

I completed a continuity test on the wiring harness between the ECM and cylinder 2, and the result shows good conductivity. The wire is intact, but no pulse is detected at the injector terminal.

Anonymous 2011-12-07 21:27

Continuity tests do not confirm signal integrity—only resistance. Perform a volt drop test to check for voltage loss along the circuit. Alternatively, install an overlay harness directly from the PCM to cylinder 2's injector and retest with a noid light. If the noid lights up properly, the original wiring has a fault. If it still doesn't respond, the issue may be a failing ECM or a defective signal driver in the module.

Anonymous 2011-12-13 11:39

I installed a new wire directly from the PCM to cylinder 2's injector and still received no pulse. The noid light does not flash. Based on this, I believe the ECM is faulty. Where can I find a reliable, affordable replacement for the ECM instead of buying it from the dealer?

Anonymous 2011-12-13 11:51

Assuming your 2003 Eclipse uses a single coil pack for all cylinders (common in older models), check the spark plug and its associated wire going to cylinder 2. If you have a shared coil pack, swap the spark plug and wire with those from another known-good cylinder (e.g., cylinder 4 or 6). Clear the codes and test after bringing the engine to operating temperature. If you have individual coil packs per cylinder (as in newer models), swap both the coil pack and spark plug between cylinders—preferably not adjacent to #2—to isolate whether the issue is ignition-related. Also, consider replacing old spark plugs as part of routine maintenance if they are worn.

Anonymous 2011-12-13 18:33

How can a faulty ignition component cause an injector driver fault? I'm confused—does a misfire due to bad spark affect the injector signal or just fuel delivery?

Anonymous 2011-12-14 10:26

Jeff Compton asked: How does a bad ignition part cause an injector driver issue? Based on my research, P0202 is typically interpreted as a faulty injector in cylinder 2. However, if the spark plug or ignition system fails, it can lead to misfires that disrupt air-fuel ratios and affect engine performance—this may indirectly trigger diagnostic codes related to fuel injection systems. That said, since the noid light shows no pulse at cylinder 2, the root issue is likely not a direct injector failure but rather an electrical signal problem. I recommend swapping the injector with one from a known-good cylinder (like #4 or #6) and clearing the code to see if it moves. This will help determine whether the fault is in the injector or the circuit.