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2004 Chevrolet SSR with P0100, P0171-P0175, P0300, P0420 and U1041: OBD-II Codes After Fuel Changes and Tuner Issues

Model: 2004 SSR Fault Code: P0100 Posted: 2015-07-13 23:47

I own a 2004 Chevrolet SSR with 129,000 miles. Since winter 2014, I've experienced recurring engine issues that started when attempting to start the vehicle after sitting in sub-45°F garage temperatures. The car would start fine initially but shortly after heater operation began, a P0420 code appeared. I shut down and waited until spring to restart. Initially, I noticed that Sunoco gasoline triggered the appearance of trouble codes, particularly P0171-P0175 and P0420. Switching to BP and Speedway fuels during summer eliminated these issues temporarily. However, in the spring, the same codes returned—mostly when idling or moving slowly in traffic—especially after using Sunoco gas (regular or 94 octane). Highway driving remained stable but fuel efficiency dropped by approximately 50%. I performed basic diagnostics: checked spark plugs, air filter, ignition system, and fuel delivery. These steps did not resolve the issue. The vehicle now displays multiple OBD-II codes: P0100 (Mass Airflow Sensor Malfunction), P0171-P0175 (Fuel Trim Issues), P0300 (Random Misfire), P0420 (Catalytic Converter Efficiency), and U1041 (Communication Issue with Body Control Module). I visited a Chevrolet dealership for diagnosis. After three hours and a $57 fee, they concluded I needed new catalytic converters at a cost of $2,500. When asked if the converters were clogged, the service manager claimed modern gasoline types are causing system damage. I attempted a DIY fix by replacing ignition components (spark plugs, coils, wires) with aftermarket parts from Rock Auto—only to discover these parts failed under load. After replacing all components with OEM-quality parts—including new Bosch O2 sensors—I still see recurring codes. I use the Diablo Predator Tuner, which maintains engine temperature below 195°F by controlling cooling fan operation. However, when switching back to the factory tune during service visits, the temperature gauge reaches 260°F—even with A/C on—indicating a potential control or thermal management issue. I recently observed lean Bank 1 and rich Bank 2 conditions at a cruise event, along with P0420. Over the past two days, I’ve rechecked all components: injectors, spark plugs (correct heat range), coils, wires, vacuum lines at fuel regulator elbow, ignition switch, and battery connections—where I found rust on the negative post affecting electrical continuity. My question is: Could the Engine Control Module (ECM) be malfunctioning? The persistent OBD-II codes, combined with inconsistent fan behavior and temperature spikes, suggest deeper system issues. I’ve spoken to other 2004 SSR owners who reported similar problems around 25,000 miles—but none have experienced my level of complexity or recurring failures. I've replaced all tires, speedometer, ABS module, brake components, radiator, water pump, high-performance cooling fan, suspension parts (shocks, A-frames), heater motor and relay. I perform all maintenance myself due to skepticism about mechanics who often recommend expensive fixes without proper diagnostics. Multiple Chevrolet parts representatives have advised that the 2004 SSR was not built as a standard vehicle—VIN verification is required at GM dealerships for accurate part matching. Over three months, I've spent over $3,000 on parts with no lasting resolution. Is this a mechanical failure or did I receive a vehicle assembled on Friday? What could be causing these persistent OBD-II codes despite multiple replacements?

Related fault codes
P0100P0171P0172P0174P0175P0300P0420U1041
Comments (5)
Anonymous 2015-07-14 13:45

Which engine variant do you have — 5.3L or 6.0L? Using aftermarket tuners like Diablo Predator can introduce issues—only use genuine GM parts. Avoid modifications such as K&N air filters, CAI, magnets, tornados, MSD components, or remote starters. Do you have an OBD-II scanner with live data capability? Note: The owner’s manual specifies 89 octane as optimal; 87 is acceptable. Using a VIN ensures correct part compatibility for engine, transmission, emissions, hardtop/convertible variants—only AutoZone offers one-size-fits-all parts.

Anonymous 2015-07-20 21:14

I have the 5.3L engine. The manual recommends 89 octane as ideal but allows 87. All installed components are from Advanced Auto Parts. I currently use a stock air filter and previously had a Spectre filter that failed to clean properly. After completing a 100-mile ride with new AC spark plugs, coils, and wires, and new fuel injectors (BDW), all O2 sensors replaced—I felt a shudder near home and the check engine light activated at a traffic light. Now I see P0175 and P0420. I'm confused about what's happening now. Yes, my Diablo Predator Tuner provides live scan data.

Anonymous 2015-07-21 00:05

My main concern is why the same OBD-II codes reappear after replacing spark plugs, wires, coils, and injectors—both with Diablo Predator tuning and factory settings. When I remove the high-performance tune and install the factory tune, the engine begins overheating. I must turn on A/C to activate cooling fans. This is precisely why I use the Diablo Tuner to manage fan operation. After fixing and replacing identical parts twice in two months, nothing has resolved the issue. I’ve spoken with other SSR owners—none have reported such persistent problems.

Anonymous 2015-07-21 00:07

If catalytic converters need replacement, where can I find them? Local auto parts stores either don’t carry or cannot order these parts. They are reportedly obsolete and no longer in production.

Anonymous 2015-07-21 11:37

You currently only see two codes: P0175 (rich condition) and P0420. For a rich condition, start with simple, low-cost fixes first—use the Diablo Predator to check fuel trims across both banks. Check the Engine Coolant Temperature Sensor (ECT). Use a fuel pressure gauge to measure pressure and observe leak-down rate at KOEO. Clean the MAF sensor. Ensure engine cooling operates in stock mode—what is your ECT reading? Did you replace the thermostat? Check underhood fuses: Engine Fan #44, Ignition Relay #9, and fan relays 1 & 2. Regarding part replacement: OBD-II codes do not indicate a failed component—they signal a system imbalance. Incorrect or misleading data may be displayed by faulty sensors or improper diagnostics.