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Fuel Injector Not Working on 2004 Cadillac CTS 3.6L - P0202 and P0302 Codes

Model: 04 CTS 3.6 Fault Code: P0218 Posted: 2018-03-10 14:05

I have replaced all fuel injectors, coil packs, and spark plugs on my 2004 Cadillac CTS with a 3.6L engine. Despite these replacements, Injector Number 2 is still not functioning. I've traced the wiring, checked resistance values, and confirmed no issues in the circuit. The Check Engine Light remains on, displaying both P0202 (Fuel Injector Circuit Malfunction) and P0302 (Cylinder 2 Misfire). After clearing the codes, the vehicle still returns with P0302 when driven. I swapped the injector from Cylinder 2 to another cylinder, but the code persisted—indicating the issue may not be solely with the injector itself.

Related fault codes
P0218P0219
Comments (6)
Anonymous 2018-03-10 16:09

Is the Check Engine Light on? What specific codes are present (e.g., P0202, P0302)? How do you confirm that Injector #2 is not firing? A clear diagnosis of symptoms and diagnostic codes is essential for accurate troubleshooting.

Anonymous 2018-03-12 08:45

The Check Engine Light is on with persistent P0202 and P0302 codes. I've replaced all coil packs, plugs, and injectors. After clearing the codes, the vehicle still shows P0302 when driven. I swapped Injector #2 with an injector from another cylinder, but the code remained—this suggests the issue may be deeper than a faulty injector.

Anonymous 2018-03-12 18:48

Are you currently only seeing P0302 or still receiving both P0202 and P0302?

Anonymous 2018-03-12 19:35

Focus on the P0202 code. Verify all wiring connections at the injector and at the Powertrain Control Module (PCM). Check if the PCM's injector driver circuit is functioning properly. A diagnostic tool like a TPIN or a multimeter can help back-probe the injector circuit. I can provide a detailed wiring diagram for testing the 3.6L CTS injector circuit using standard test procedures.

Anonymous 2018-03-13 14:26

Currently, only P0302 is present. I've confirmed that the coil pack is firing and that the wiring is intact. The Injector #2 is not activating—traced wires show no issues.

Anonymous 2018-03-13 18:01

This could be an 'international shutdown' scenario where the PCM disables Injector #2 due to a misfire in Cylinder #2, protecting the catalytic converter. A stuck-open or excessively leaking injector (dirty or high-flow) may cause this. If swapping injectors doesn't resolve P0302, rule out a faulty injector or coil pack. Misfires can also stem from weak spark, vacuum leaks, or low compression in Cylinder #2. To confirm if it's an intentional shutdown: clear the codes and use a Noid light to monitor injector pulse during startup. If the Noid light flashes on Injector #2 after starting but stops immediately—this indicates a PCM-driven shutdown. You mentioned replacing all injectors; was Injector #2 previously shorted? A short could have damaged the PCM's injector driver circuit. If you connect a Noid light to Injector #2, clear codes, and start the engine with no flash, this points to a faulty driver inside the PCM. While an oscilloscope is ideal for testing, a simple test light can also verify injector driver integrity.