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2000 Trans Am WS6 LS1 P0171 and P0174 Codes After EGR and Air Pump Removal with SLP Headers

Model: 2000 Trans Am Fault Code: P0171 Posted: 2017-12-31 12:55

I recently installed SLP headers with high-flow catalytic converters and an ORY pipe on my 2000 Trans Am WS6 with the LS1 engine. I also performed an EGR delete and air pump removal, and had the ECM reprogrammed to remove these components. After the modifications, I'm now receiving OBD-II diagnostic codes P0171 (System Too Lean Bank 1) and P0174 (System Too Lean Bank 2). This was not an issue before the modifications. The car is currently at 60,000 miles with all stock components except for a hood lid. I'm concerned about what might be causing these lean conditions. Could the removal of emission controls or the headers be responsible? Any insights or troubleshooting steps would be greatly appreciated.

Related fault codes
P0171P0174
Comments (5)
Anonymous 2018-01-02 11:15

I installed SLP headers with high-flow cats and a catted Y-pipe. I removed both EGR and air pump components, had the ECM reprogrammed to reflect these changes, and all codes were cleared — no SES light appeared. However, I'm now seeing P0171 and P0174. Anyone else experiencing this? It's a 2000 Trans Am WS6 with LS1 engine. Thanks for any advice.

Anonymous 2018-07-20 17:40

Check for vacuum leaks — perform a smoke test if visual inspection doesn't reveal any obvious sources.

Anonymous 2018-07-20 19:00

There are many potential causes of lean conditions. Monitor your oxygen sensor readings and fuel trims under various driving conditions. This article provides a helpful breakdown for diagnosing lean-related issues: https://www.obd2diagnostictips.com/blog/understanding-p0171-lean-condition

Anonymous 2018-07-21 08:25

First — it's illegal to remove or disable emission controls under most regulations. The P0171 and P0174 codes indicate a lean condition. Use an OBD2 scanner to check ECT temperature, fuel trims, and oxygen sensor voltages. Avoid using K&N air filters without proper tuning. Verify fuel pressure is within specifications. As suggested, perform a vacuum leak test with carb cleaner — spray around all hoses and connections quickly and watch for engine hesitation or changes in performance.

Anonymous 2019-01-31 11:01

I have a Cadillac Escalade Base MOD with a 6.0L LS1 engine. After installing a K&N air intake, throttle body spacer, BBK short-tube headers, MagnaFlow exhaust, and a lower-end performance chip, I started receiving P0171 and P0174 codes. I focused on the PCV system and hoses for leaks — found a moderate leak in the bank 2 header. I also used carb cleaner to test for vacuum leaks, but no other sources were identified. Any suggestions? Still looking for help!