Two O2 sensors on the 4.0L inline-six; four on the 4.7L V8. The exact count depends on the engine installed in your 2004 Grand Cherokee.
Engine options and sensor counts
The 2004 Grand Cherokee offered at least two engines, and each uses a different O2-sensor arrangement. Here's the typical setup by engine.
- 4.0L inline-six (I6): 2 O2 sensors — one upstream (before the catalytic converter) and one downstream (after it).
- 4.7L V8: 4 O2 sensors — two upstream sensors (one for each bank) and two downstream sensors (one after each bank's catalytic converter).
These counts reflect standard exhaust layouts used on the 2004 Grand Cherokee. Verify by checking the vehicle's service records or by inspecting the exhaust system, since trims or emissions packages can vary by market or special editions.
Sensor locations and quick checks
In practical terms, the sensors sit along the exhaust path. The upstream sensors are closest to the engine, monitoring the air-fuel mix before the catalytic converter. The downstream sensors, after the catalytic converter, monitor the converter's effectiveness and feed data to the engine's computer for fine-tuning and emissions reporting. If your check-engine light is on or you’re diagnosing an emissions issue, count the sensors along the exhaust headers or collectors to confirm the expected configuration for your engine.
Summary
In short, the 2004 Jeep Grand Cherokee can have either two or four O2 sensors, depending on engine choice: two for the 4.0L inline-six and four for the 4.7L V8. When diagnosing faults or replacing sensors, target the correct count based on your engine to avoid errors and ensure proper emissions monitoring.