🚨 Diagnostic Profile
Vehicle Make: BUICK
Code: Throttle Position (TP) Sensor 1-2 Correlation
This diagnostic trouble code indicates a discrepancy between the signal readings of the two internal throttle position sensors housed within the electronic throttle body. The Engine Control Module (ECM) continuously cross-checks these two sensors for plausibility; when their voltage outputs do not correlate within the expected range during a given throttle input, the ECM flags this correlation fault and may default to a reduced power or ‘limp’ mode to maintain safe vehicle operation.
🚨 Repair Difficulty Tier
Difficulty Rating: Intermediate
This repair falls into the Intermediate category. While replacing the throttle body assembly itself involves straightforward hand tools, accurately diagnosing this code requires a capable scan tool to view live, synchronized data from both TP sensors simultaneously, as well as a digital multimeter to verify wiring integrity, reference voltage, and ground circuits. A basic mechanical knowledge of electronic throttle control (ETC) systems is necessary, though no specialized module programming is typically required unless throttle body relearn procedures are needed post-repair.
🛠️ Resolution Steps
Step 1: Preliminary Inspection
Begin with a visual inspection of the throttle body assembly and its wiring harness. Check for:
– Corrosion, bent pins, or moisture intrusion at the throttle body electrical connector
– Damaged, chafed, or pinched wiring leading to the throttle position sensors
– Visible carbon buildup or physical damage on the throttle plate and bore that could cause mechanical binding
– Secure and properly seated harness connectors at the ECM
Step 2: Diagnostic Verification
Connect a scan tool capable of displaying live data streams for TP Sensor 1 and TP Sensor 2 simultaneously. With the key on and engine off, slowly manipulate the throttle (if accessible) or have an assistant depress the accelerator pedal while monitoring:
– Both sensor voltage outputs should move in a complementary, predictable, and correlated pattern (typically one rises while the other falls, or both move proportionally depending on sensor design)
– Look for dropouts, erratic spikes, or a sensor that remains static while the other changes
– Backprobe the connector with a multimeter to verify reference voltage (typically 5V), ground integrity, and signal output voltages independently of the scan tool data
– Compare live data against manufacturer-specified voltage ranges at idle and wide-open throttle
Step 3: Resolution & Reset Process
If wiring and connectors test within specification but sensor correlation remains faulty, replacement of the electronic throttle body assembly (which houses both TP sensors as a non-serviceable unit) is required. After installation:
– Clear existing diagnostic trouble codes using the scan tool
– Perform a throttle body relearn or idle relearn procedure as specified by the manufacturer, which may involve a key-cycle sequence or scan tool-initiated relearn
– Road test the vehicle while monitoring live data to confirm both sensors now correlate properly across the full range of throttle movement
– Verify no additional codes have set during the test drive
📦 Parts, Labor, and Budget Estimates
Required Components/Software: Electronic throttle body assembly (OEM recommended), diagnostic scan tool with live data and bi-directional capability, digital multimeter, dielectric grease for connector reassembly
Average Component Price: $150 – $350 for the throttle body assembly, depending on the specific Buick model and year; no special software flashing is typically required beyond standard relearn procedures
Estimated Labor Hours: 1.0 – 1.5 hours for diagnosis, plus 0.5 – 1.0 hour for throttle body replacement and relearn procedure (total estimated shop time: 1.5 – 2.5 hours)