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Ron Z.
Ron Z., - Chevy Tech -
Category: Chevy
Satisfied Customers: 18334
Experience:  18+yrs experience. State Inspector and Chevy Diagnostics
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Just washed engine with a garden hose and now have a po741

Customer Question

just washed engine with a garden hose and now have a po741 and a po742 code.
JA: Have you scanned the code? Have you tried to reset it?
Customer: yes but haven't driven car again to check it
JA: What is the make/model/year of your car?
Customer: 02 cavalier
JA: Are you hoping to fix this yourself? What have you tried so far?
Customer: yes . have not tried anything yet. just researching code
JA: Anything else you think the mechanic should know?
Customer: yes, I'm not sure about fluid level as I just recently changed fluid and filter because of a pan gasket leak but car was running/shifting fine after service. could fluid level be a issue ?
JA: OK. Got it. I'm sending you to a secure page on JustAnswer so you can place the $5 fully-refundable deposit now. While you're filling out that form, I'll tell the Mechanic about your situation and then connect you two.
Submitted: 8 months ago.
Category: Chevy
Expert:  Ron Z. replied 8 months ago.

Both of these codes are related and both point to a problem with the Transmission Fluid Pressure Switch Assembly. This switch is located inside the transmission side cover attached to the valve body. This very well could be related to the recent fluid and filter service. This code will set when there is a rapid change in pressure (like when fluid is drained and then refilled- pressure goes from low to high very quickly). It can also set if pressure is too low or too high (under-filled/over-filled). So, first, check the fluid level. If the level is good, I would recommend clearing the codes by removing the NEG cable from the battery for 5 minutes, as this could just be a byproduct of the recent service. If the code returns, then you'll need to look into the TFP switch as it may have been damaged due to the fluid service. If you found this answer helpful, please help me by leaving a rating using the "stars" at the top of the page or click 'accept'.
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