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2008 Dodge Magnum Check Engine Light On: P0325, P0688, C2100, C220, U140E Fault Codes Explained

Model: 08 Dodge Magnum Fault Code: C2100 Posted: 2016-01-28 18:19

The check engine light has come on in my 2008 Dodge Magnum and remains steady. A diagnostic scan reveals several fault codes: P0325 (Knock Sensor Circuit Malfunction - Bank 1), P0688 (Fuel Level Sensor Circuit Malfunction), C2100 (Low Battery Voltage), C220 (ABS System Fault), and U140E (Transmission Control Module Communication Issue). The initial scan also reported a VIN mismatch, which may be a software or data entry error. I have no prior issues with the vehicle until recently. After installing a new rack and pinion, multiple warning lights began appearing — including ABS, Skid, and ESP — which remain on steadily. The engine runs smoothly without knocking or tapping, but the check engine light flickers when hitting bumps. I suspect a loose knock sensor wiring harness, especially given that the symptom correlates with vehicle movement. However, I'm now concerned about whether the rack and pinion replacement triggered broader electronic system issues. Could these codes be related to mechanical changes? What should I do next to diagnose and fix this properly?

Related fault codes
C2100P0325P0688
Comments (11)
Anonymous 2016-01-29 08:39

Is this vehicle stock? Any modifications or aftermarket parts installed (e.g., wheels, suspension, performance upgrades)?

Anonymous 2016-06-09 19:14

When you mention 'mods,' do you mean any after-market additions like wheels, suspension, audio systems, or performance components? I'm experiencing the same check engine light and would appreciate detailed help.

Anonymous 2016-06-09 19:16

I have 22-inch aftermarket rims. What counts as a modification or add-on? As a female user, I’m not sure what 'stock' means in this context.

Anonymous 2016-06-09 19:50

kev2 wrote: Is this vehicle stock? No mods or add-ons? I don’t understand what you mean by 'mods' or 'add-ons.'

Anonymous 2016-06-10 10:07

Modifications refer to any component not originally included in the vehicle's factory build. Examples include remote starters, alarms, audio systems, lighting upgrades, or performance parts. Could you confirm your engine type? (2.7L, 3.5L, 5.7L, or 6.1L?) Did the installation of the 22-inch wheels trigger any programming issues in your vehicle's ECU? Was the ABS light on before or after installing the new wheels?

Anonymous 2016-06-10 11:35

Apologies for the fragmented replies. Your 2008 Dodge Magnum suddenly developed these codes. To better understand, I’d like some key details: - What engine do you have? (Ensure correct model identification) - How long have you owned this vehicle? Could there be pre-existing issues? - Did any of the symptoms appear after installing the 22-inch wheels? Several faults may relate to wheel or suspension changes. - Was the ABS light on before or after the wheels were installed? - Is the engine running quietly with no exhaust leaks, knocking, or tapping? Has it ever run out of fuel? With this information, we can better assess and prioritize possible causes. PS: This is not a simple DIY fix and requires professional tools and knowledge.

Anonymous 2016-06-19 20:33

No — when I replaced the rack and pinion, all warning lights came on. The check engine light turns on or off when I hit bumps, which may indicate a loose knock sensor wiring connection.

Anonymous 2016-06-19 20:40

Only the check engine light was initially active. I suspect a loose knock sensor cable. After replacing the rack and pinion, ABS, Skid, and ESP lights all came on and remain steady. Any advice would be greatly appreciated.

Anonymous 2016-06-22 07:04

The other warning lights did not appear when the wheels were installed. I have a 2.7L engine. The check engine light flickers during bumps — this is likely due to a loose knock sensor wire. After replacing the rack and pinion, all other systems (ABS, ESP, Skid) turned on and remain steady. No knocking or tapping occurs; the engine runs smoothly.

Anonymous 2016-06-22 07:31

You should consult a professional technician. Did you perform the rack and pinion replacement yourself? It may be worth revisiting that service shop. These fault codes are complex and not easily resolved by DIY methods. A proper diagnostic requires a professional scanner, access to wiring diagrams, and in-depth understanding of vehicle systems — this is beyond typical do-it-yourself capability.

Anonymous 2016-06-22 22:31

OK, thanks. I believe the issue started after installing the rack and pinion — likely due to improper steering column alignment or misaligned tires. That was the first time I experienced these symptoms.