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2003 Dodge Neon P0480 Code: Diagnosis, Fan Relay Issues, and Code Reset Problems

Model: 2003 Dodge Neon Fault Code: P0480 Posted: 2016-02-03 16:36

I'm experiencing a persistent P0480 diagnostic trouble code on my 2003 Dodge Neon 2.0L (non-turbo). The code indicates an open or shorted circuit in the radiator fan relay control circuit. I replaced both the temperature sensor and the low-speed radiator fan relay. After testing, I found that when I bypassed the relay using a jumper wire, the fans activated — confirming the issue was likely with the relay or its wiring. I then connected a toggle switch directly to the fan wires and confirmed that the fans operate properly when the switch is on. However, once the car starts, the P0480 code reappears immediately and will not reset. Turning off the fan switch does not prevent the code from returning. The fans previously failed to work for a long time, but the P0480 code did not appear until recently. This suggests the fault may have developed gradually or been masked by other conditions. I've tried resetting the code using a scan tool, but it comes back as soon as I start the engine. No wiring diagram is available to me currently, and I'm unsure if there's a separate low-speed fan relay in this model — only one relay was found in the relay box. Both fans activate when the air conditioning is turned on, which indicates that the fan motor itself is functional. However, the control circuit remains faulty, preventing the code from clearing. I've cleaned all ground connections and rechecked the temperature sensor wiring, and everything appears correct according to online references. After restarting the car and letting it warm up, the fans briefly activated twice before shutting off — a sign of intermittent operation but not full functionality. I'm seeking advice on how to properly diagnose and fix this issue, especially regarding relay resistance, control circuit continuity, and whether any modifications or aftermarket parts could have triggered this fault.

Related fault codes
P0480
Comments (7)
Anonymous 2016-02-03 17:25

The P0480 code specifically indicates an open or shorted circuit in the radiator fan relay control circuit. For a 2003 Dodge Neon with a 2.0L non-turbo engine, this is a common issue. Possible causes include: faulty low-speed radiator fan relay, blown fuses in the B+ power feed, high resistance in the relay, or an open/shorted control circuit. Do you have access to a wiring diagram for your model year and engine size? This would help verify the correct wiring path.

Anonymous 2016-02-04 09:46

Yes, it's a 2.0L non-turbo. I only found one fan relay in the relay box — is there a separate low-speed fan relay or could this be a common issue with shared relays? The P0480 code has never appeared before now, even though the fans weren't working for months. After installing a toggle switch to power the fans directly, everything worked fine for about 50 miles. Then suddenly, the P0480 code started flashing and won’t reset. I’ve tried turning off the fan switch — no effect. The code returns immediately when starting the car. No wiring diagram is available to me currently.

Anonymous 2016-02-06 00:34

Both fans activate when the air conditioning is turned on, which confirms they are mechanically functional. However, the P0480 code persists and will not clear — even after multiple resets. Any suggestions for diagnosing the control circuit or relay resistance would be greatly appreciated.

Anonymous 2016-02-06 08:52

This could potentially be an SRT4 model with a 2.4L engine, which has different components. Missing details like engine size and trim level can significantly affect diagnosis — please confirm whether your vehicle is a standard 2.0L or a higher-trim variant.

Anonymous 2016-02-06 21:27

It's confirmed as a 2.0L model. The fans have been non-functional for months, but the P0480 code didn’t appear until recently. I ran a hot wire from a toggle switch directly to the fan wires — everything worked fine for about 50 miles. Then suddenly, the P0480 code started flashing and won't reset. Even with the switch off, the code remains active. This suggests a deeper electrical fault that didn’t manifest earlier. I believe a wiring or relay issue is present but not immediately obvious.

Anonymous 2016-02-07 09:00

Use an OBD2 scanner to retrieve and post all diagnostic codes — not just P0480. This helps identify any related issues (e.g., other fault codes). I'm having trouble finding a wiring diagram for the 2003 Neon 2.0L with dual fans. Also, have you made any modifications or installed aftermarket parts? If so, those could be contributing factors. Please share full details — and double-check that you're not using a modified relay setup.

Anonymous 2016-02-08 08:28

I disassembled the battery tray to access the temperature sensor and cleaned all ground connections thoroughly. I also inspected both sides of the temperature sensor plug, which matched online specifications. After reassembly and starting the car, the fans briefly activated twice before shutting off — a sign that they are responsive but not fully reliable. This suggests intermittent control circuit issues. The fact that the fans work when powered directly via a toggle switch confirms the motors are functional, pointing to a problem in the relay or its control wiring.