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John, ASE Master Technician
Category: Chevy
Satisfied Customers: 614
Experience:  ASE Certified Master Technician, ASE Certified Service Consultant, 22 years professional experience
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I have a 99 chevy 1500 246k on it I got the p1870 code and

Customer Question

I have a 99 chevy 1500 246k on it I got the p1870 code and feels like tranny slips when warm it says its the valve body
JA: Sometimes things that you think will be really complicated end up being easy to fix with Chevy. The Chevy Mechanic I'm going to connect you with knows all the tricks and shortcuts. Tell me a bit more about what's going on so he can help you best.
Customer: whe cold id don't slip or anything but when you accelerate fast it tends to slip or rev up while not enguaging just started lastnight and have the p1870 code in my dtc
JA: The mechanics can certainly get you off to the right "start" -- sorry! Sometimes I can't help myself;-) Seriously, though, the mechanics are real masters when it comes to fixing things, and it would be my pleasure to put you in touch with the best one for this. Are you hoping to fix this yourself?
Customer: possibly I work at a shop
JA: Is there anything else important you think the Chevy Mechanic should know about your Chevy?
Customer: motor has headers cold air intake throttle body spacer and it has two other codes p0171 fuel trim system lean bank 1 and a p0174 fuel trim system lean bank 2
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 Chevy Mechanic about your situation and then connect you two.
Submitted: 1 year ago.
Category: Chevy
Customer: replied 1 year ago.
Expert:  John replied 1 year ago.
Hello, my name is***** is basically a code for a slipping transmission component. This can be caused by a problem in the valve body, usually wear in the valve body. Typically it starts with a hard shift. There is a TSB from GM about this that states the haed shifts begin in the 1-2 shift. As far as the P0171 and P0174 codes, they refer to a lean running condition. This may be relevant to the transmission problem if the cause of the codes is the mass air flow sensor. When the mass air flow sensor reads incorrectly it has a negative effect on fuel trim which could explain the lean codes. Also, the transmission takes a load signal from the mass air flow sensor to help decide when to shift. So, if the mass ir flow sensor is feeding bad info to the transmission then the transmission can suffer damage as a result. In anycase, you could replace the valve body in your transmission but depending on the extent of the damage from the transmission slipping you might just plan on replacing the whole transmission. SInce you work in a shop I can help you do some tests on the mass air flow sensor and on the transmission if you have a scanner you can use to read data from the PCM. Let me know how you want to proceed and I will do what I can to help.John
Expert:  John replied 1 year ago.
Just following up to see what you have found. Please let me know if you have any further questions,or, if you found my information helpful please rate my information positive.Thank you.