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2005 S40 2.4. Code P0172 and Suspension Issues

Old 03-10-2019, 10:51 AM
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Join Date: Mar 2019
Posts: 7
Default 2005 S40 2.4. Code P0172 and Suspension Issues

Hello All,

New to forum. Acquired a used S40, 116k from my niece. I have a few issues. Searched on other forums, etc. just canít find solution. So, I am hoping this post and your help will create a solution. Thank you.

2005 S40 2.4, 116k miles
-Code P0172 bank 1 system too rich
-Replaced MAF, Fuel Pressure Sensor, Fuel Pump, Spark Plugs and had Injectors cleaned.
-New fuel pump (Bosch) is making a whining sound 2min after start up. Had fuel pressure checked and all seems good (50-60psi). Note:this pump also includes the filter (ie lifetime. Lol)
- Same Code Reappears a few minutes after clearing
-O2 is original but mech said itís fine?
-Throttle Body Cleaned
-Checked all vacuum hoses included Crankhose to oil housing. All seem fine. Mech confirmed
Any help in trouble shooting will be helpful. Note: I replaced the fuel pump myself. The noise/loud squeal started 2 weeks later for what that is worth.

- Pulls hard left. And I sometimes (not consistent) get a bad clunk over small bumps or turning wheel either way??
-Had 3 alignments in as many weeks. Steering wheel is straight when car pulls ​​​​​
-Control arms just replaced
-Axles just replaced
-brakes just replaced
-Tie Rods, Bushings, Sway Links checked and said where fine
-Replaced Top passenger side engine mount.
-Tires are new and have been rebalanced and remounted.

Timing Belt (kit) replaced last week by Volvo.

-Stuts are original but said to be fine.


Last edited by toolagit2qwit; 03-10-2019 at 10:56 AM.
Old 03-10-2019, 11:34 AM
Join Date: Mar 2012
Location: Ridgefield, CT
Posts: 4,591

Regarding the suspension - the thump going over speed bumps/ RR tracks etc suggest you have a strut mount/ strut bearing issue. This could also affect the alignment as your strut may be centered when an the alignment rack but off center when driving or turning. Do you see any signs of an accident (possibly a bent strut?). Usually when a tech says a strut is fine, they can only see if its leaking oil or has lost its rebound. You may want to consider replacing the front struts and redo the bushing/bearings.

On the mixture issue - any signs of an exhaust leak? This can impact the O2 sensor. How does the car idle? The throttle body may still be the cause - there's contacts that can get corroded so being clean is just the first step. Another thing to check out is the engine coolant temp sensor. easy enough to replace for $50, and you can do the t-stat at the same time. Also, don't give up on finding an intake air leak. You may need to do a smoke test as some of the rubber bits can be hidden under the manifold and other parts and not easily inspected.

Search the board for other posts on the P0172 - most solutions point to either vacuum leaks, exhaust leaks, O2 sensors, ECT sensors, ETMs (electronic throttle mechanism), fuel pressure regulators/dampers or sensors (your model may not have a regulator...).
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